Commit | Line | Data |
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237fead6 MH |
1 | /** |
2 | * eCryptfs: Linux filesystem encryption layer | |
3 | * This is where eCryptfs coordinates the symmetric encryption and | |
4 | * decryption of the file data as it passes between the lower | |
5 | * encrypted file and the upper decrypted file. | |
6 | * | |
7 | * Copyright (C) 1997-2003 Erez Zadok | |
8 | * Copyright (C) 2001-2003 Stony Brook University | |
dd2a3b7a | 9 | * Copyright (C) 2004-2007 International Business Machines Corp. |
237fead6 MH |
10 | * Author(s): Michael A. Halcrow <mahalcro@us.ibm.com> |
11 | * | |
12 | * This program is free software; you can redistribute it and/or | |
13 | * modify it under the terms of the GNU General Public License as | |
14 | * published by the Free Software Foundation; either version 2 of the | |
15 | * License, or (at your option) any later version. | |
16 | * | |
17 | * This program is distributed in the hope that it will be useful, but | |
18 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
20 | * General Public License for more details. | |
21 | * | |
22 | * You should have received a copy of the GNU General Public License | |
23 | * along with this program; if not, write to the Free Software | |
24 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA | |
25 | * 02111-1307, USA. | |
26 | */ | |
27 | ||
28 | #include <linux/pagemap.h> | |
29 | #include <linux/writeback.h> | |
30 | #include <linux/page-flags.h> | |
31 | #include <linux/mount.h> | |
32 | #include <linux/file.h> | |
33 | #include <linux/crypto.h> | |
34 | #include <linux/scatterlist.h> | |
35 | #include "ecryptfs_kernel.h" | |
36 | ||
37 | struct kmem_cache *ecryptfs_lower_page_cache; | |
38 | ||
39 | /** | |
16a72c45 | 40 | * ecryptfs_get_locked_page |
237fead6 MH |
41 | * |
42 | * Get one page from cache or lower f/s, return error otherwise. | |
43 | * | |
16a72c45 | 44 | * Returns locked and up-to-date page (if ok), with increased |
237fead6 MH |
45 | * refcnt. |
46 | */ | |
16a72c45 | 47 | struct page *ecryptfs_get_locked_page(struct file *file, loff_t index) |
237fead6 | 48 | { |
237fead6 MH |
49 | struct dentry *dentry; |
50 | struct inode *inode; | |
51 | struct address_space *mapping; | |
16a72c45 | 52 | struct page *page; |
237fead6 | 53 | |
bd243a4b | 54 | dentry = file->f_path.dentry; |
237fead6 MH |
55 | inode = dentry->d_inode; |
56 | mapping = inode->i_mapping; | |
16a72c45 MH |
57 | page = read_mapping_page(mapping, index, (void *)file); |
58 | if (!IS_ERR(page)) | |
59 | lock_page(page); | |
60 | return page; | |
237fead6 MH |
61 | } |
62 | ||
237fead6 MH |
63 | /** |
64 | * ecryptfs_writepage | |
65 | * @page: Page that is locked before this call is made | |
66 | * | |
67 | * Returns zero on success; non-zero otherwise | |
68 | */ | |
69 | static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc) | |
70 | { | |
237fead6 MH |
71 | int rc; |
72 | ||
0216f7f7 | 73 | rc = ecryptfs_encrypt_page(page); |
237fead6 MH |
74 | if (rc) { |
75 | ecryptfs_printk(KERN_WARNING, "Error encrypting " | |
76 | "page (upper index [0x%.16x])\n", page->index); | |
77 | ClearPageUptodate(page); | |
78 | goto out; | |
79 | } | |
80 | SetPageUptodate(page); | |
81 | unlock_page(page); | |
82 | out: | |
83 | return rc; | |
84 | } | |
85 | ||
e77a56dd MH |
86 | /** |
87 | * Header Extent: | |
88 | * Octets 0-7: Unencrypted file size (big-endian) | |
89 | * Octets 8-15: eCryptfs special marker | |
90 | * Octets 16-19: Flags | |
91 | * Octet 16: File format version number (between 0 and 255) | |
92 | * Octets 17-18: Reserved | |
93 | * Octet 19: Bit 1 (lsb): Reserved | |
94 | * Bit 2: Encrypted? | |
95 | * Bits 3-8: Reserved | |
96 | * Octets 20-23: Header extent size (big-endian) | |
97 | * Octets 24-25: Number of header extents at front of file | |
98 | * (big-endian) | |
99 | * Octet 26: Begin RFC 2440 authentication token packet set | |
100 | */ | |
101 | static void set_header_info(char *page_virt, | |
102 | struct ecryptfs_crypt_stat *crypt_stat) | |
103 | { | |
104 | size_t written; | |
105 | int save_num_header_extents_at_front = | |
106 | crypt_stat->num_header_extents_at_front; | |
107 | ||
108 | crypt_stat->num_header_extents_at_front = 1; | |
109 | ecryptfs_write_header_metadata(page_virt + 20, crypt_stat, &written); | |
110 | crypt_stat->num_header_extents_at_front = | |
111 | save_num_header_extents_at_front; | |
112 | } | |
237fead6 | 113 | |
bf12be1c MH |
114 | /** |
115 | * ecryptfs_copy_up_encrypted_with_header | |
116 | * @page: Sort of a ``virtual'' representation of the encrypted lower | |
117 | * file. The actual lower file does not have the metadata in | |
118 | * the header. This is locked. | |
119 | * @crypt_stat: The eCryptfs inode's cryptographic context | |
120 | * | |
121 | * The ``view'' is the version of the file that userspace winds up | |
122 | * seeing, with the header information inserted. | |
123 | */ | |
124 | static int | |
125 | ecryptfs_copy_up_encrypted_with_header(struct page *page, | |
126 | struct ecryptfs_crypt_stat *crypt_stat) | |
127 | { | |
128 | loff_t extent_num_in_page = 0; | |
129 | loff_t num_extents_per_page = (PAGE_CACHE_SIZE | |
130 | / crypt_stat->extent_size); | |
131 | int rc = 0; | |
132 | ||
133 | while (extent_num_in_page < num_extents_per_page) { | |
d6a13c17 MH |
134 | loff_t view_extent_num = ((((loff_t)page->index) |
135 | * num_extents_per_page) | |
bf12be1c MH |
136 | + extent_num_in_page); |
137 | ||
138 | if (view_extent_num < crypt_stat->num_header_extents_at_front) { | |
139 | /* This is a header extent */ | |
140 | char *page_virt; | |
141 | ||
142 | page_virt = kmap_atomic(page, KM_USER0); | |
143 | memset(page_virt, 0, PAGE_CACHE_SIZE); | |
144 | /* TODO: Support more than one header extent */ | |
145 | if (view_extent_num == 0) { | |
146 | rc = ecryptfs_read_xattr_region( | |
147 | page_virt, page->mapping->host); | |
148 | set_header_info(page_virt, crypt_stat); | |
149 | } | |
150 | kunmap_atomic(page_virt, KM_USER0); | |
151 | flush_dcache_page(page); | |
152 | if (rc) { | |
bf12be1c MH |
153 | printk(KERN_ERR "%s: Error reading xattr " |
154 | "region; rc = [%d]\n", __FUNCTION__, rc); | |
155 | goto out; | |
156 | } | |
bf12be1c MH |
157 | } else { |
158 | /* This is an encrypted data extent */ | |
159 | loff_t lower_offset = | |
160 | ((view_extent_num - | |
161 | crypt_stat->num_header_extents_at_front) | |
162 | * crypt_stat->extent_size); | |
163 | ||
164 | rc = ecryptfs_read_lower_page_segment( | |
165 | page, (lower_offset >> PAGE_CACHE_SHIFT), | |
166 | (lower_offset & ~PAGE_CACHE_MASK), | |
167 | crypt_stat->extent_size, page->mapping->host); | |
168 | if (rc) { | |
169 | printk(KERN_ERR "%s: Error attempting to read " | |
170 | "extent at offset [%lld] in the lower " | |
171 | "file; rc = [%d]\n", __FUNCTION__, | |
172 | lower_offset, rc); | |
173 | goto out; | |
174 | } | |
175 | } | |
176 | extent_num_in_page++; | |
177 | } | |
178 | out: | |
179 | return rc; | |
180 | } | |
181 | ||
237fead6 MH |
182 | /** |
183 | * ecryptfs_readpage | |
bf12be1c MH |
184 | * @file: An eCryptfs file |
185 | * @page: Page from eCryptfs inode mapping into which to stick the read data | |
237fead6 MH |
186 | * |
187 | * Read in a page, decrypting if necessary. | |
188 | * | |
189 | * Returns zero on success; non-zero on error. | |
190 | */ | |
191 | static int ecryptfs_readpage(struct file *file, struct page *page) | |
192 | { | |
bf12be1c MH |
193 | struct ecryptfs_crypt_stat *crypt_stat = |
194 | &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)->crypt_stat; | |
237fead6 | 195 | int rc = 0; |
237fead6 | 196 | |
237fead6 | 197 | if (!crypt_stat |
e2bd99ec MH |
198 | || !(crypt_stat->flags & ECRYPTFS_ENCRYPTED) |
199 | || (crypt_stat->flags & ECRYPTFS_NEW_FILE)) { | |
237fead6 MH |
200 | ecryptfs_printk(KERN_DEBUG, |
201 | "Passing through unencrypted page\n"); | |
bf12be1c MH |
202 | rc = ecryptfs_read_lower_page_segment(page, page->index, 0, |
203 | PAGE_CACHE_SIZE, | |
204 | page->mapping->host); | |
e77a56dd MH |
205 | } else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) { |
206 | if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) { | |
bf12be1c MH |
207 | rc = ecryptfs_copy_up_encrypted_with_header(page, |
208 | crypt_stat); | |
209 | if (rc) { | |
210 | printk(KERN_ERR "%s: Error attempting to copy " | |
211 | "the encrypted content from the lower " | |
212 | "file whilst inserting the metadata " | |
213 | "from the xattr into the header; rc = " | |
214 | "[%d]\n", __FUNCTION__, rc); | |
215 | goto out; | |
e77a56dd | 216 | } |
bf12be1c | 217 | |
e77a56dd | 218 | } else { |
bf12be1c MH |
219 | rc = ecryptfs_read_lower_page_segment( |
220 | page, page->index, 0, PAGE_CACHE_SIZE, | |
221 | page->mapping->host); | |
e77a56dd MH |
222 | if (rc) { |
223 | printk(KERN_ERR "Error reading page; rc = " | |
224 | "[%d]\n", rc); | |
225 | goto out; | |
226 | } | |
227 | } | |
237fead6 | 228 | } else { |
0216f7f7 | 229 | rc = ecryptfs_decrypt_page(page); |
237fead6 | 230 | if (rc) { |
237fead6 MH |
231 | ecryptfs_printk(KERN_ERR, "Error decrypting page; " |
232 | "rc = [%d]\n", rc); | |
233 | goto out; | |
234 | } | |
235 | } | |
237fead6 | 236 | out: |
16a72c45 MH |
237 | if (rc) |
238 | ClearPageUptodate(page); | |
239 | else | |
240 | SetPageUptodate(page); | |
237fead6 MH |
241 | ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n", |
242 | page->index); | |
243 | unlock_page(page); | |
244 | return rc; | |
245 | } | |
246 | ||
dd2a3b7a MH |
247 | /** |
248 | * Called with lower inode mutex held. | |
249 | */ | |
237fead6 MH |
250 | static int fill_zeros_to_end_of_page(struct page *page, unsigned int to) |
251 | { | |
252 | struct inode *inode = page->mapping->host; | |
253 | int end_byte_in_page; | |
237fead6 | 254 | |
9d8b8ce5 MH |
255 | if ((i_size_read(inode) / PAGE_CACHE_SIZE) != page->index) |
256 | goto out; | |
257 | end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE; | |
258 | if (to > end_byte_in_page) | |
259 | end_byte_in_page = to; | |
c9f2875b ND |
260 | zero_user_page(page, end_byte_in_page, |
261 | PAGE_CACHE_SIZE - end_byte_in_page, KM_USER0); | |
237fead6 | 262 | out: |
9d8b8ce5 | 263 | return 0; |
237fead6 MH |
264 | } |
265 | ||
266 | static int ecryptfs_prepare_write(struct file *file, struct page *page, | |
267 | unsigned from, unsigned to) | |
268 | { | |
269 | int rc = 0; | |
270 | ||
237fead6 MH |
271 | if (from == 0 && to == PAGE_CACHE_SIZE) |
272 | goto out; /* If we are writing a full page, it will be | |
273 | up to date. */ | |
16a72c45 | 274 | if (!PageUptodate(page)) { |
bf12be1c MH |
275 | rc = ecryptfs_read_lower_page_segment(page, page->index, 0, |
276 | PAGE_CACHE_SIZE, | |
277 | page->mapping->host); | |
16a72c45 MH |
278 | if (rc) { |
279 | printk(KERN_ERR "%s: Error attemping to read lower " | |
280 | "page segment; rc = [%d]\n", __FUNCTION__, rc); | |
281 | ClearPageUptodate(page); | |
282 | goto out; | |
283 | } else | |
284 | SetPageUptodate(page); | |
285 | } | |
240e2df5 | 286 | if (page->index != 0) { |
bf12be1c MH |
287 | loff_t end_of_prev_pg_pos = |
288 | (((loff_t)page->index << PAGE_CACHE_SHIFT) - 1); | |
240e2df5 MH |
289 | |
290 | if (end_of_prev_pg_pos > i_size_read(page->mapping->host)) { | |
291 | rc = ecryptfs_truncate(file->f_path.dentry, | |
292 | end_of_prev_pg_pos); | |
293 | if (rc) { | |
294 | printk(KERN_ERR "Error on attempt to " | |
295 | "truncate to (higher) offset [%lld];" | |
296 | " rc = [%d]\n", end_of_prev_pg_pos, rc); | |
297 | goto out; | |
298 | } | |
53a2731f | 299 | } |
d4c5cdb3 MH |
300 | if (end_of_prev_pg_pos + 1 > i_size_read(page->mapping->host)) |
301 | zero_user_page(page, 0, PAGE_CACHE_SIZE, KM_USER0); | |
53a2731f | 302 | } |
237fead6 MH |
303 | out: |
304 | return rc; | |
305 | } | |
306 | ||
237fead6 MH |
307 | /** |
308 | * ecryptfs_write_inode_size_to_header | |
309 | * | |
310 | * Writes the lower file size to the first 8 bytes of the header. | |
311 | * | |
312 | * Returns zero on success; non-zero on error. | |
313 | */ | |
0216f7f7 | 314 | static int ecryptfs_write_inode_size_to_header(struct inode *ecryptfs_inode) |
237fead6 | 315 | { |
237fead6 | 316 | u64 file_size; |
0216f7f7 MH |
317 | char *file_size_virt; |
318 | int rc; | |
237fead6 | 319 | |
0216f7f7 MH |
320 | file_size_virt = kmalloc(sizeof(u64), GFP_KERNEL); |
321 | if (!file_size_virt) { | |
322 | rc = -ENOMEM; | |
ae73fc09 MH |
323 | goto out; |
324 | } | |
0216f7f7 | 325 | file_size = (u64)i_size_read(ecryptfs_inode); |
237fead6 | 326 | file_size = cpu_to_be64(file_size); |
0216f7f7 MH |
327 | memcpy(file_size_virt, &file_size, sizeof(u64)); |
328 | rc = ecryptfs_write_lower(ecryptfs_inode, file_size_virt, 0, | |
329 | sizeof(u64)); | |
330 | kfree(file_size_virt); | |
331 | if (rc) | |
332 | printk(KERN_ERR "%s: Error writing file size to header; " | |
333 | "rc = [%d]\n", __FUNCTION__, rc); | |
237fead6 MH |
334 | out: |
335 | return rc; | |
336 | } | |
337 | ||
0216f7f7 MH |
338 | struct kmem_cache *ecryptfs_xattr_cache; |
339 | ||
340 | static int ecryptfs_write_inode_size_to_xattr(struct inode *ecryptfs_inode) | |
dd2a3b7a MH |
341 | { |
342 | ssize_t size; | |
343 | void *xattr_virt; | |
0216f7f7 MH |
344 | struct dentry *lower_dentry = |
345 | ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_dentry; | |
346 | struct inode *lower_inode = lower_dentry->d_inode; | |
dd2a3b7a MH |
347 | u64 file_size; |
348 | int rc; | |
349 | ||
0216f7f7 MH |
350 | if (!lower_inode->i_op->getxattr || !lower_inode->i_op->setxattr) { |
351 | printk(KERN_WARNING | |
352 | "No support for setting xattr in lower filesystem\n"); | |
353 | rc = -ENOSYS; | |
354 | goto out; | |
355 | } | |
dd2a3b7a MH |
356 | xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL); |
357 | if (!xattr_virt) { | |
358 | printk(KERN_ERR "Out of memory whilst attempting to write " | |
359 | "inode size to xattr\n"); | |
360 | rc = -ENOMEM; | |
361 | goto out; | |
362 | } | |
0216f7f7 MH |
363 | mutex_lock(&lower_inode->i_mutex); |
364 | size = lower_inode->i_op->getxattr(lower_dentry, ECRYPTFS_XATTR_NAME, | |
365 | xattr_virt, PAGE_CACHE_SIZE); | |
dd2a3b7a MH |
366 | if (size < 0) |
367 | size = 8; | |
0216f7f7 | 368 | file_size = (u64)i_size_read(ecryptfs_inode); |
dd2a3b7a MH |
369 | file_size = cpu_to_be64(file_size); |
370 | memcpy(xattr_virt, &file_size, sizeof(u64)); | |
0216f7f7 MH |
371 | rc = lower_inode->i_op->setxattr(lower_dentry, ECRYPTFS_XATTR_NAME, |
372 | xattr_virt, size, 0); | |
373 | mutex_unlock(&lower_inode->i_mutex); | |
dd2a3b7a MH |
374 | if (rc) |
375 | printk(KERN_ERR "Error whilst attempting to write inode size " | |
376 | "to lower file xattr; rc = [%d]\n", rc); | |
377 | kmem_cache_free(ecryptfs_xattr_cache, xattr_virt); | |
378 | out: | |
379 | return rc; | |
380 | } | |
381 | ||
0216f7f7 | 382 | int ecryptfs_write_inode_size_to_metadata(struct inode *ecryptfs_inode) |
dd2a3b7a MH |
383 | { |
384 | struct ecryptfs_crypt_stat *crypt_stat; | |
385 | ||
0216f7f7 | 386 | crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat; |
dd2a3b7a | 387 | if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) |
0216f7f7 | 388 | return ecryptfs_write_inode_size_to_xattr(ecryptfs_inode); |
dd2a3b7a | 389 | else |
0216f7f7 | 390 | return ecryptfs_write_inode_size_to_header(ecryptfs_inode); |
dd2a3b7a MH |
391 | } |
392 | ||
237fead6 MH |
393 | /** |
394 | * ecryptfs_commit_write | |
395 | * @file: The eCryptfs file object | |
396 | * @page: The eCryptfs page | |
397 | * @from: Ignored (we rotate the page IV on each write) | |
398 | * @to: Ignored | |
399 | * | |
400 | * This is where we encrypt the data and pass the encrypted data to | |
401 | * the lower filesystem. In OpenPGP-compatible mode, we operate on | |
402 | * entire underlying packets. | |
403 | */ | |
404 | static int ecryptfs_commit_write(struct file *file, struct page *page, | |
405 | unsigned from, unsigned to) | |
406 | { | |
237fead6 | 407 | loff_t pos; |
bf12be1c MH |
408 | struct inode *ecryptfs_inode = page->mapping->host; |
409 | struct ecryptfs_crypt_stat *crypt_stat = | |
410 | &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)->crypt_stat; | |
237fead6 MH |
411 | int rc; |
412 | ||
e2bd99ec | 413 | if (crypt_stat->flags & ECRYPTFS_NEW_FILE) { |
237fead6 MH |
414 | ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in " |
415 | "crypt_stat at memory location [%p]\n", crypt_stat); | |
e2bd99ec | 416 | crypt_stat->flags &= ~(ECRYPTFS_NEW_FILE); |
237fead6 MH |
417 | } else |
418 | ecryptfs_printk(KERN_DEBUG, "Not a new file\n"); | |
419 | ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page" | |
420 | "(page w/ index = [0x%.16x], to = [%d])\n", page->index, | |
421 | to); | |
bf12be1c | 422 | /* Fills in zeros if 'to' goes beyond inode size */ |
237fead6 MH |
423 | rc = fill_zeros_to_end_of_page(page, to); |
424 | if (rc) { | |
425 | ecryptfs_printk(KERN_WARNING, "Error attempting to fill " | |
426 | "zeros in page with index = [0x%.16x]\n", | |
427 | page->index); | |
428 | goto out; | |
429 | } | |
0216f7f7 | 430 | rc = ecryptfs_encrypt_page(page); |
237fead6 MH |
431 | if (rc) { |
432 | ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper " | |
433 | "index [0x%.16x])\n", page->index); | |
434 | goto out; | |
435 | } | |
d6a13c17 | 436 | pos = (((loff_t)page->index) << PAGE_CACHE_SHIFT) + to; |
bf12be1c MH |
437 | if (pos > i_size_read(ecryptfs_inode)) { |
438 | i_size_write(ecryptfs_inode, pos); | |
237fead6 | 439 | ecryptfs_printk(KERN_DEBUG, "Expanded file size to " |
bf12be1c | 440 | "[0x%.16x]\n", i_size_read(ecryptfs_inode)); |
237fead6 | 441 | } |
bf12be1c | 442 | rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode); |
dd2a3b7a MH |
443 | if (rc) |
444 | printk(KERN_ERR "Error writing inode size to metadata; " | |
445 | "rc = [%d]\n", rc); | |
237fead6 | 446 | out: |
237fead6 MH |
447 | return rc; |
448 | } | |
449 | ||
237fead6 MH |
450 | static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block) |
451 | { | |
452 | int rc = 0; | |
453 | struct inode *inode; | |
454 | struct inode *lower_inode; | |
455 | ||
456 | inode = (struct inode *)mapping->host; | |
457 | lower_inode = ecryptfs_inode_to_lower(inode); | |
458 | if (lower_inode->i_mapping->a_ops->bmap) | |
459 | rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping, | |
460 | block); | |
461 | return rc; | |
462 | } | |
463 | ||
237fead6 MH |
464 | struct address_space_operations ecryptfs_aops = { |
465 | .writepage = ecryptfs_writepage, | |
466 | .readpage = ecryptfs_readpage, | |
467 | .prepare_write = ecryptfs_prepare_write, | |
468 | .commit_write = ecryptfs_commit_write, | |
469 | .bmap = ecryptfs_bmap, | |
237fead6 | 470 | }; |