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Jaegeuk Kim6b3bd082015-04-26 00:12:50 -07001/*
2 * linux/fs/f2fs/crypto_fname.c
3 *
4 * Copied from linux/fs/ext4/crypto.c
5 *
6 * Copyright (C) 2015, Google, Inc.
7 * Copyright (C) 2015, Motorola Mobility
8 *
9 * This contains functions for filename crypto management in f2fs
10 *
11 * Written by Uday Savagaonkar, 2014.
12 *
13 * Adjust f2fs dentry structure
14 * Jaegeuk Kim, 2015.
15 *
16 * This has not yet undergone a rigorous security audit.
17 */
18#include <crypto/hash.h>
19#include <crypto/sha.h>
20#include <keys/encrypted-type.h>
21#include <keys/user-type.h>
22#include <linux/crypto.h>
23#include <linux/gfp.h>
24#include <linux/kernel.h>
25#include <linux/key.h>
26#include <linux/list.h>
27#include <linux/mempool.h>
28#include <linux/random.h>
29#include <linux/scatterlist.h>
30#include <linux/spinlock_types.h>
31#include <linux/f2fs_fs.h>
32#include <linux/ratelimit.h>
33
34#include "f2fs.h"
35#include "f2fs_crypto.h"
36#include "xattr.h"
37
38/**
39 * f2fs_dir_crypt_complete() -
40 */
41static void f2fs_dir_crypt_complete(struct crypto_async_request *req, int res)
42{
43 struct f2fs_completion_result *ecr = req->data;
44
45 if (res == -EINPROGRESS)
46 return;
47 ecr->res = res;
48 complete(&ecr->completion);
49}
50
51bool f2fs_valid_filenames_enc_mode(uint32_t mode)
52{
53 return (mode == F2FS_ENCRYPTION_MODE_AES_256_CTS);
54}
55
56static unsigned max_name_len(struct inode *inode)
57{
58 return S_ISLNK(inode->i_mode) ? inode->i_sb->s_blocksize :
59 F2FS_NAME_LEN;
60}
61
62/**
63 * f2fs_fname_encrypt() -
64 *
65 * This function encrypts the input filename, and returns the length of the
66 * ciphertext. Errors are returned as negative numbers. We trust the caller to
67 * allocate sufficient memory to oname string.
68 */
69static int f2fs_fname_encrypt(struct inode *inode,
70 const struct qstr *iname, struct f2fs_str *oname)
71{
72 u32 ciphertext_len;
73 struct ablkcipher_request *req = NULL;
74 DECLARE_F2FS_COMPLETION_RESULT(ecr);
75 struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
76 struct crypto_ablkcipher *tfm = ci->ci_ctfm;
77 int res = 0;
78 char iv[F2FS_CRYPTO_BLOCK_SIZE];
79 struct scatterlist src_sg, dst_sg;
80 int padding = 4 << (ci->ci_flags & F2FS_POLICY_FLAGS_PAD_MASK);
81 char *workbuf, buf[32], *alloc_buf = NULL;
82 unsigned lim = max_name_len(inode);
83
84 if (iname->len <= 0 || iname->len > lim)
85 return -EIO;
86
87 ciphertext_len = (iname->len < F2FS_CRYPTO_BLOCK_SIZE) ?
88 F2FS_CRYPTO_BLOCK_SIZE : iname->len;
89 ciphertext_len = f2fs_fname_crypto_round_up(ciphertext_len, padding);
90 ciphertext_len = (ciphertext_len > lim) ? lim : ciphertext_len;
91
92 if (ciphertext_len <= sizeof(buf)) {
93 workbuf = buf;
94 } else {
95 alloc_buf = kmalloc(ciphertext_len, GFP_NOFS);
96 if (!alloc_buf)
97 return -ENOMEM;
98 workbuf = alloc_buf;
99 }
100
101 /* Allocate request */
102 req = ablkcipher_request_alloc(tfm, GFP_NOFS);
103 if (!req) {
104 printk_ratelimited(KERN_ERR
105 "%s: crypto_request_alloc() failed\n", __func__);
106 kfree(alloc_buf);
107 return -ENOMEM;
108 }
109 ablkcipher_request_set_callback(req,
110 CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
111 f2fs_dir_crypt_complete, &ecr);
112
113 /* Copy the input */
114 memcpy(workbuf, iname->name, iname->len);
115 if (iname->len < ciphertext_len)
116 memset(workbuf + iname->len, 0, ciphertext_len - iname->len);
117
118 /* Initialize IV */
119 memset(iv, 0, F2FS_CRYPTO_BLOCK_SIZE);
120
121 /* Create encryption request */
122 sg_init_one(&src_sg, workbuf, ciphertext_len);
123 sg_init_one(&dst_sg, oname->name, ciphertext_len);
124 ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, ciphertext_len, iv);
125 res = crypto_ablkcipher_encrypt(req);
126 if (res == -EINPROGRESS || res == -EBUSY) {
127 BUG_ON(req->base.data != &ecr);
128 wait_for_completion(&ecr.completion);
129 res = ecr.res;
130 }
131 kfree(alloc_buf);
132 ablkcipher_request_free(req);
133 if (res < 0) {
134 printk_ratelimited(KERN_ERR
135 "%s: Error (error code %d)\n", __func__, res);
136 }
137 oname->len = ciphertext_len;
138 return res;
139}
140
141/*
142 * f2fs_fname_decrypt()
143 * This function decrypts the input filename, and returns
144 * the length of the plaintext.
145 * Errors are returned as negative numbers.
146 * We trust the caller to allocate sufficient memory to oname string.
147 */
148static int f2fs_fname_decrypt(struct inode *inode,
149 const struct f2fs_str *iname, struct f2fs_str *oname)
150{
151 struct ablkcipher_request *req = NULL;
152 DECLARE_F2FS_COMPLETION_RESULT(ecr);
153 struct scatterlist src_sg, dst_sg;
154 struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
155 struct crypto_ablkcipher *tfm = ci->ci_ctfm;
156 int res = 0;
157 char iv[F2FS_CRYPTO_BLOCK_SIZE];
158 unsigned lim = max_name_len(inode);
159
160 if (iname->len <= 0 || iname->len > lim)
161 return -EIO;
162
163 /* Allocate request */
164 req = ablkcipher_request_alloc(tfm, GFP_NOFS);
165 if (!req) {
166 printk_ratelimited(KERN_ERR
167 "%s: crypto_request_alloc() failed\n", __func__);
168 return -ENOMEM;
169 }
170 ablkcipher_request_set_callback(req,
171 CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
172 f2fs_dir_crypt_complete, &ecr);
173
174 /* Initialize IV */
175 memset(iv, 0, F2FS_CRYPTO_BLOCK_SIZE);
176
177 /* Create decryption request */
178 sg_init_one(&src_sg, iname->name, iname->len);
179 sg_init_one(&dst_sg, oname->name, oname->len);
180 ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, iv);
181 res = crypto_ablkcipher_decrypt(req);
182 if (res == -EINPROGRESS || res == -EBUSY) {
183 BUG_ON(req->base.data != &ecr);
184 wait_for_completion(&ecr.completion);
185 res = ecr.res;
186 }
187 ablkcipher_request_free(req);
188 if (res < 0) {
189 printk_ratelimited(KERN_ERR
190 "%s: Error in f2fs_fname_decrypt (error code %d)\n",
191 __func__, res);
192 return res;
193 }
194
195 oname->len = strnlen(oname->name, iname->len);
196 return oname->len;
197}
198
199static const char *lookup_table =
200 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
201
202/**
203 * f2fs_fname_encode_digest() -
204 *
205 * Encodes the input digest using characters from the set [a-zA-Z0-9_+].
206 * The encoded string is roughly 4/3 times the size of the input string.
207 */
208static int digest_encode(const char *src, int len, char *dst)
209{
210 int i = 0, bits = 0, ac = 0;
211 char *cp = dst;
212
213 while (i < len) {
214 ac += (((unsigned char) src[i]) << bits);
215 bits += 8;
216 do {
217 *cp++ = lookup_table[ac & 0x3f];
218 ac >>= 6;
219 bits -= 6;
220 } while (bits >= 6);
221 i++;
222 }
223 if (bits)
224 *cp++ = lookup_table[ac & 0x3f];
225 return cp - dst;
226}
227
228static int digest_decode(const char *src, int len, char *dst)
229{
230 int i = 0, bits = 0, ac = 0;
231 const char *p;
232 char *cp = dst;
233
234 while (i < len) {
235 p = strchr(lookup_table, src[i]);
236 if (p == NULL || src[i] == 0)
237 return -2;
238 ac += (p - lookup_table) << bits;
239 bits += 6;
240 if (bits >= 8) {
241 *cp++ = ac & 0xff;
242 ac >>= 8;
243 bits -= 8;
244 }
245 i++;
246 }
247 if (ac)
248 return -1;
249 return cp - dst;
250}
251
Jaegeuk Kim6b3bd082015-04-26 00:12:50 -0700252/**
253 * f2fs_fname_crypto_round_up() -
254 *
255 * Return: The next multiple of block size
256 */
257u32 f2fs_fname_crypto_round_up(u32 size, u32 blksize)
258{
259 return ((size + blksize - 1) / blksize) * blksize;
260}
261
262/**
263 * f2fs_fname_crypto_alloc_obuff() -
264 *
265 * Allocates an output buffer that is sufficient for the crypto operation
266 * specified by the context and the direction.
267 */
268int f2fs_fname_crypto_alloc_buffer(struct inode *inode,
269 u32 ilen, struct f2fs_str *crypto_str)
270{
271 unsigned int olen;
272 int padding = 16;
273 struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
274
275 if (ci)
276 padding = 4 << (ci->ci_flags & F2FS_POLICY_FLAGS_PAD_MASK);
277 if (padding < F2FS_CRYPTO_BLOCK_SIZE)
278 padding = F2FS_CRYPTO_BLOCK_SIZE;
279 olen = f2fs_fname_crypto_round_up(ilen, padding);
280 crypto_str->len = olen;
281 if (olen < F2FS_FNAME_CRYPTO_DIGEST_SIZE * 2)
282 olen = F2FS_FNAME_CRYPTO_DIGEST_SIZE * 2;
283 /* Allocated buffer can hold one more character to null-terminate the
284 * string */
285 crypto_str->name = kmalloc(olen + 1, GFP_NOFS);
286 if (!(crypto_str->name))
287 return -ENOMEM;
288 return 0;
289}
290
291/**
292 * f2fs_fname_crypto_free_buffer() -
293 *
294 * Frees the buffer allocated for crypto operation.
295 */
296void f2fs_fname_crypto_free_buffer(struct f2fs_str *crypto_str)
297{
298 if (!crypto_str)
299 return;
300 kfree(crypto_str->name);
301 crypto_str->name = NULL;
302}
303
304/**
305 * f2fs_fname_disk_to_usr() - converts a filename from disk space to user space
306 */
307int f2fs_fname_disk_to_usr(struct inode *inode,
308 f2fs_hash_t *hash,
309 const struct f2fs_str *iname,
310 struct f2fs_str *oname)
311{
312 const struct qstr qname = FSTR_TO_QSTR(iname);
313 char buf[24];
314 int ret;
315
316 if (is_dot_dotdot(&qname)) {
317 oname->name[0] = '.';
318 oname->name[iname->len - 1] = '.';
319 oname->len = iname->len;
320 return oname->len;
321 }
322
323 if (F2FS_I(inode)->i_crypt_info)
324 return f2fs_fname_decrypt(inode, iname, oname);
325
326 if (iname->len <= F2FS_FNAME_CRYPTO_DIGEST_SIZE) {
327 ret = digest_encode(iname->name, iname->len, oname->name);
328 oname->len = ret;
329 return ret;
330 }
331 if (hash) {
332 memcpy(buf, hash, 4);
333 memset(buf + 4, 0, 4);
334 } else
335 memset(buf, 0, 8);
336 memcpy(buf + 8, iname->name + iname->len - 16, 16);
337 oname->name[0] = '_';
338 ret = digest_encode(buf, 24, oname->name + 1);
339 oname->len = ret + 1;
340 return ret + 1;
341}
342
343/**
344 * f2fs_fname_usr_to_disk() - converts a filename from user space to disk space
345 */
346int f2fs_fname_usr_to_disk(struct inode *inode,
347 const struct qstr *iname,
348 struct f2fs_str *oname)
349{
350 int res;
351 struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
352
353 if (is_dot_dotdot(iname)) {
354 oname->name[0] = '.';
355 oname->name[iname->len - 1] = '.';
356 oname->len = iname->len;
357 return oname->len;
358 }
359
360 if (ci) {
361 res = f2fs_fname_encrypt(inode, iname, oname);
362 return res;
363 }
364 /* Without a proper key, a user is not allowed to modify the filenames
365 * in a directory. Consequently, a user space name cannot be mapped to
366 * a disk-space name */
367 return -EACCES;
368}
369
370int f2fs_fname_setup_filename(struct inode *dir, const struct qstr *iname,
371 int lookup, struct f2fs_filename *fname)
372{
373 struct f2fs_crypt_info *ci;
374 int ret = 0, bigname = 0;
375
376 memset(fname, 0, sizeof(struct f2fs_filename));
377 fname->usr_fname = iname;
378
379 if (!f2fs_encrypted_inode(dir) || is_dot_dotdot(iname)) {
380 fname->disk_name.name = (unsigned char *)iname->name;
381 fname->disk_name.len = iname->len;
Chao Yu7bf4b552015-05-13 18:20:54 +0800382 return 0;
Jaegeuk Kim6b3bd082015-04-26 00:12:50 -0700383 }
Jaegeuk Kim26bf3dc2015-05-19 22:26:54 -0700384 ret = f2fs_get_encryption_info(dir);
Jaegeuk Kim6b3bd082015-04-26 00:12:50 -0700385 if (ret)
386 return ret;
387 ci = F2FS_I(dir)->i_crypt_info;
388 if (ci) {
389 ret = f2fs_fname_crypto_alloc_buffer(dir, iname->len,
390 &fname->crypto_buf);
391 if (ret < 0)
Chao Yu7bf4b552015-05-13 18:20:54 +0800392 return ret;
Jaegeuk Kim6b3bd082015-04-26 00:12:50 -0700393 ret = f2fs_fname_encrypt(dir, iname, &fname->crypto_buf);
394 if (ret < 0)
Jaegeuk Kime5e09062015-05-28 17:06:40 -0700395 goto errout;
Jaegeuk Kim6b3bd082015-04-26 00:12:50 -0700396 fname->disk_name.name = fname->crypto_buf.name;
397 fname->disk_name.len = fname->crypto_buf.len;
Chao Yu7bf4b552015-05-13 18:20:54 +0800398 return 0;
Jaegeuk Kim6b3bd082015-04-26 00:12:50 -0700399 }
Jaegeuk Kime5e09062015-05-28 17:06:40 -0700400 if (!lookup)
401 return -EACCES;
Jaegeuk Kim6b3bd082015-04-26 00:12:50 -0700402
403 /* We don't have the key and we are doing a lookup; decode the
404 * user-supplied name
405 */
406 if (iname->name[0] == '_')
407 bigname = 1;
408 if ((bigname && (iname->len != 33)) ||
Jaegeuk Kime5e09062015-05-28 17:06:40 -0700409 (!bigname && (iname->len > 43)))
410 return -ENOENT;
411
Jaegeuk Kim6b3bd082015-04-26 00:12:50 -0700412 fname->crypto_buf.name = kmalloc(32, GFP_KERNEL);
Jaegeuk Kime5e09062015-05-28 17:06:40 -0700413 if (fname->crypto_buf.name == NULL)
414 return -ENOMEM;
Jaegeuk Kim6b3bd082015-04-26 00:12:50 -0700415 ret = digest_decode(iname->name + bigname, iname->len - bigname,
416 fname->crypto_buf.name);
417 if (ret < 0) {
418 ret = -ENOENT;
Jaegeuk Kime5e09062015-05-28 17:06:40 -0700419 goto errout;
Jaegeuk Kim6b3bd082015-04-26 00:12:50 -0700420 }
421 fname->crypto_buf.len = ret;
422 if (bigname) {
423 memcpy(&fname->hash, fname->crypto_buf.name, 4);
424 } else {
425 fname->disk_name.name = fname->crypto_buf.name;
426 fname->disk_name.len = fname->crypto_buf.len;
427 }
Chao Yu7bf4b552015-05-13 18:20:54 +0800428 return 0;
Jaegeuk Kime5e09062015-05-28 17:06:40 -0700429errout:
Chao Yu7bf4b552015-05-13 18:20:54 +0800430 f2fs_fname_crypto_free_buffer(&fname->crypto_buf);
Jaegeuk Kim6b3bd082015-04-26 00:12:50 -0700431 return ret;
432}
433
434void f2fs_fname_free_filename(struct f2fs_filename *fname)
435{
436 kfree(fname->crypto_buf.name);
437 fname->crypto_buf.name = NULL;
438 fname->usr_fname = NULL;
439 fname->disk_name.name = NULL;
440}