Commit | Line | Data |
---|---|---|
6b3bd08f | 1 | /* |
0b81d077 | 2 | * This contains functions for filename crypto management |
6b3bd08f JK |
3 | * |
4 | * Copyright (C) 2015, Google, Inc. | |
5 | * Copyright (C) 2015, Motorola Mobility | |
6 | * | |
6b3bd08f | 7 | * Written by Uday Savagaonkar, 2014. |
0b81d077 | 8 | * Modified by Jaegeuk Kim, 2015. |
6b3bd08f JK |
9 | * |
10 | * This has not yet undergone a rigorous security audit. | |
11 | */ | |
0b81d077 | 12 | |
6b3bd08f | 13 | #include <linux/scatterlist.h> |
6b3bd08f | 14 | #include <linux/ratelimit.h> |
0b81d077 | 15 | #include <linux/fscrypto.h> |
6b3bd08f | 16 | |
6b3bd08f | 17 | /** |
53fd7550 EB |
18 | * fname_crypt_complete() - completion callback for filename crypto |
19 | * @req: The asynchronous cipher request context | |
20 | * @res: The result of the cipher operation | |
6b3bd08f | 21 | */ |
53fd7550 | 22 | static void fname_crypt_complete(struct crypto_async_request *req, int res) |
6b3bd08f | 23 | { |
0b81d077 | 24 | struct fscrypt_completion_result *ecr = req->data; |
6b3bd08f JK |
25 | |
26 | if (res == -EINPROGRESS) | |
27 | return; | |
28 | ecr->res = res; | |
29 | complete(&ecr->completion); | |
30 | } | |
31 | ||
6b3bd08f | 32 | /** |
ef1eb3aa | 33 | * fname_encrypt() - encrypt a filename |
6b3bd08f | 34 | * |
ef1eb3aa EB |
35 | * The caller must have allocated sufficient memory for the @oname string. |
36 | * | |
37 | * Return: 0 on success, -errno on failure | |
6b3bd08f | 38 | */ |
0b81d077 JK |
39 | static int fname_encrypt(struct inode *inode, |
40 | const struct qstr *iname, struct fscrypt_str *oname) | |
6b3bd08f JK |
41 | { |
42 | u32 ciphertext_len; | |
2731a944 | 43 | struct skcipher_request *req = NULL; |
0b81d077 JK |
44 | DECLARE_FS_COMPLETION_RESULT(ecr); |
45 | struct fscrypt_info *ci = inode->i_crypt_info; | |
2731a944 | 46 | struct crypto_skcipher *tfm = ci->ci_ctfm; |
6b3bd08f | 47 | int res = 0; |
0b81d077 | 48 | char iv[FS_CRYPTO_BLOCK_SIZE]; |
6b3bd08f | 49 | struct scatterlist src_sg, dst_sg; |
0b81d077 | 50 | int padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK); |
6b3bd08f | 51 | char *workbuf, buf[32], *alloc_buf = NULL; |
0b81d077 | 52 | unsigned lim; |
6b3bd08f | 53 | |
0b81d077 | 54 | lim = inode->i_sb->s_cop->max_namelen(inode); |
6b3bd08f JK |
55 | if (iname->len <= 0 || iname->len > lim) |
56 | return -EIO; | |
57 | ||
55be3145 EB |
58 | ciphertext_len = max(iname->len, (u32)FS_CRYPTO_BLOCK_SIZE); |
59 | ciphertext_len = round_up(ciphertext_len, padding); | |
60 | ciphertext_len = min(ciphertext_len, lim); | |
6b3bd08f JK |
61 | |
62 | if (ciphertext_len <= sizeof(buf)) { | |
63 | workbuf = buf; | |
64 | } else { | |
65 | alloc_buf = kmalloc(ciphertext_len, GFP_NOFS); | |
66 | if (!alloc_buf) | |
67 | return -ENOMEM; | |
68 | workbuf = alloc_buf; | |
69 | } | |
70 | ||
71 | /* Allocate request */ | |
2731a944 | 72 | req = skcipher_request_alloc(tfm, GFP_NOFS); |
6b3bd08f JK |
73 | if (!req) { |
74 | printk_ratelimited(KERN_ERR | |
75 | "%s: crypto_request_alloc() failed\n", __func__); | |
76 | kfree(alloc_buf); | |
77 | return -ENOMEM; | |
78 | } | |
2731a944 | 79 | skcipher_request_set_callback(req, |
6b3bd08f | 80 | CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, |
53fd7550 | 81 | fname_crypt_complete, &ecr); |
6b3bd08f JK |
82 | |
83 | /* Copy the input */ | |
84 | memcpy(workbuf, iname->name, iname->len); | |
85 | if (iname->len < ciphertext_len) | |
86 | memset(workbuf + iname->len, 0, ciphertext_len - iname->len); | |
87 | ||
88 | /* Initialize IV */ | |
0b81d077 | 89 | memset(iv, 0, FS_CRYPTO_BLOCK_SIZE); |
6b3bd08f JK |
90 | |
91 | /* Create encryption request */ | |
92 | sg_init_one(&src_sg, workbuf, ciphertext_len); | |
93 | sg_init_one(&dst_sg, oname->name, ciphertext_len); | |
2731a944 HX |
94 | skcipher_request_set_crypt(req, &src_sg, &dst_sg, ciphertext_len, iv); |
95 | res = crypto_skcipher_encrypt(req); | |
6b3bd08f | 96 | if (res == -EINPROGRESS || res == -EBUSY) { |
6b3bd08f JK |
97 | wait_for_completion(&ecr.completion); |
98 | res = ecr.res; | |
99 | } | |
100 | kfree(alloc_buf); | |
2731a944 | 101 | skcipher_request_free(req); |
ef1eb3aa | 102 | if (res < 0) { |
6b3bd08f JK |
103 | printk_ratelimited(KERN_ERR |
104 | "%s: Error (error code %d)\n", __func__, res); | |
ef1eb3aa EB |
105 | return res; |
106 | } | |
0b81d077 | 107 | |
6b3bd08f | 108 | oname->len = ciphertext_len; |
ef1eb3aa | 109 | return 0; |
6b3bd08f JK |
110 | } |
111 | ||
ef1eb3aa EB |
112 | /** |
113 | * fname_decrypt() - decrypt a filename | |
114 | * | |
115 | * The caller must have allocated sufficient memory for the @oname string. | |
116 | * | |
117 | * Return: 0 on success, -errno on failure | |
6b3bd08f | 118 | */ |
0b81d077 JK |
119 | static int fname_decrypt(struct inode *inode, |
120 | const struct fscrypt_str *iname, | |
121 | struct fscrypt_str *oname) | |
6b3bd08f | 122 | { |
2731a944 | 123 | struct skcipher_request *req = NULL; |
0b81d077 | 124 | DECLARE_FS_COMPLETION_RESULT(ecr); |
6b3bd08f | 125 | struct scatterlist src_sg, dst_sg; |
0b81d077 | 126 | struct fscrypt_info *ci = inode->i_crypt_info; |
2731a944 | 127 | struct crypto_skcipher *tfm = ci->ci_ctfm; |
6b3bd08f | 128 | int res = 0; |
0b81d077 JK |
129 | char iv[FS_CRYPTO_BLOCK_SIZE]; |
130 | unsigned lim; | |
6b3bd08f | 131 | |
0b81d077 | 132 | lim = inode->i_sb->s_cop->max_namelen(inode); |
6b3bd08f JK |
133 | if (iname->len <= 0 || iname->len > lim) |
134 | return -EIO; | |
135 | ||
136 | /* Allocate request */ | |
2731a944 | 137 | req = skcipher_request_alloc(tfm, GFP_NOFS); |
6b3bd08f JK |
138 | if (!req) { |
139 | printk_ratelimited(KERN_ERR | |
140 | "%s: crypto_request_alloc() failed\n", __func__); | |
141 | return -ENOMEM; | |
142 | } | |
2731a944 | 143 | skcipher_request_set_callback(req, |
6b3bd08f | 144 | CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, |
53fd7550 | 145 | fname_crypt_complete, &ecr); |
6b3bd08f JK |
146 | |
147 | /* Initialize IV */ | |
0b81d077 | 148 | memset(iv, 0, FS_CRYPTO_BLOCK_SIZE); |
6b3bd08f JK |
149 | |
150 | /* Create decryption request */ | |
151 | sg_init_one(&src_sg, iname->name, iname->len); | |
152 | sg_init_one(&dst_sg, oname->name, oname->len); | |
2731a944 HX |
153 | skcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, iv); |
154 | res = crypto_skcipher_decrypt(req); | |
6b3bd08f | 155 | if (res == -EINPROGRESS || res == -EBUSY) { |
6b3bd08f JK |
156 | wait_for_completion(&ecr.completion); |
157 | res = ecr.res; | |
158 | } | |
2731a944 | 159 | skcipher_request_free(req); |
6b3bd08f JK |
160 | if (res < 0) { |
161 | printk_ratelimited(KERN_ERR | |
0b81d077 | 162 | "%s: Error (error code %d)\n", __func__, res); |
6b3bd08f JK |
163 | return res; |
164 | } | |
165 | ||
166 | oname->len = strnlen(oname->name, iname->len); | |
ef1eb3aa | 167 | return 0; |
6b3bd08f JK |
168 | } |
169 | ||
170 | static const char *lookup_table = | |
171 | "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,"; | |
172 | ||
173 | /** | |
0b81d077 | 174 | * digest_encode() - |
6b3bd08f JK |
175 | * |
176 | * Encodes the input digest using characters from the set [a-zA-Z0-9_+]. | |
177 | * The encoded string is roughly 4/3 times the size of the input string. | |
178 | */ | |
179 | static int digest_encode(const char *src, int len, char *dst) | |
180 | { | |
181 | int i = 0, bits = 0, ac = 0; | |
182 | char *cp = dst; | |
183 | ||
184 | while (i < len) { | |
185 | ac += (((unsigned char) src[i]) << bits); | |
186 | bits += 8; | |
187 | do { | |
188 | *cp++ = lookup_table[ac & 0x3f]; | |
189 | ac >>= 6; | |
190 | bits -= 6; | |
191 | } while (bits >= 6); | |
192 | i++; | |
193 | } | |
194 | if (bits) | |
195 | *cp++ = lookup_table[ac & 0x3f]; | |
196 | return cp - dst; | |
197 | } | |
198 | ||
199 | static int digest_decode(const char *src, int len, char *dst) | |
200 | { | |
201 | int i = 0, bits = 0, ac = 0; | |
202 | const char *p; | |
203 | char *cp = dst; | |
204 | ||
205 | while (i < len) { | |
206 | p = strchr(lookup_table, src[i]); | |
207 | if (p == NULL || src[i] == 0) | |
208 | return -2; | |
209 | ac += (p - lookup_table) << bits; | |
210 | bits += 6; | |
211 | if (bits >= 8) { | |
212 | *cp++ = ac & 0xff; | |
213 | ac >>= 8; | |
214 | bits -= 8; | |
215 | } | |
216 | i++; | |
217 | } | |
218 | if (ac) | |
219 | return -1; | |
220 | return cp - dst; | |
221 | } | |
222 | ||
0b81d077 | 223 | u32 fscrypt_fname_encrypted_size(struct inode *inode, u32 ilen) |
6b3bd08f | 224 | { |
922ec355 | 225 | int padding = 32; |
0b81d077 | 226 | struct fscrypt_info *ci = inode->i_crypt_info; |
922ec355 CY |
227 | |
228 | if (ci) | |
0b81d077 | 229 | padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK); |
55be3145 EB |
230 | ilen = max(ilen, (u32)FS_CRYPTO_BLOCK_SIZE); |
231 | return round_up(ilen, padding); | |
6b3bd08f | 232 | } |
0b81d077 | 233 | EXPORT_SYMBOL(fscrypt_fname_encrypted_size); |
6b3bd08f JK |
234 | |
235 | /** | |
0b81d077 | 236 | * fscrypt_fname_crypto_alloc_obuff() - |
6b3bd08f JK |
237 | * |
238 | * Allocates an output buffer that is sufficient for the crypto operation | |
239 | * specified by the context and the direction. | |
240 | */ | |
0b81d077 JK |
241 | int fscrypt_fname_alloc_buffer(struct inode *inode, |
242 | u32 ilen, struct fscrypt_str *crypto_str) | |
6b3bd08f | 243 | { |
0b81d077 | 244 | unsigned int olen = fscrypt_fname_encrypted_size(inode, ilen); |
6b3bd08f | 245 | |
6b3bd08f | 246 | crypto_str->len = olen; |
0b81d077 JK |
247 | if (olen < FS_FNAME_CRYPTO_DIGEST_SIZE * 2) |
248 | olen = FS_FNAME_CRYPTO_DIGEST_SIZE * 2; | |
249 | /* | |
250 | * Allocated buffer can hold one more character to null-terminate the | |
251 | * string | |
252 | */ | |
6b3bd08f JK |
253 | crypto_str->name = kmalloc(olen + 1, GFP_NOFS); |
254 | if (!(crypto_str->name)) | |
255 | return -ENOMEM; | |
256 | return 0; | |
257 | } | |
0b81d077 | 258 | EXPORT_SYMBOL(fscrypt_fname_alloc_buffer); |
6b3bd08f JK |
259 | |
260 | /** | |
0b81d077 | 261 | * fscrypt_fname_crypto_free_buffer() - |
6b3bd08f JK |
262 | * |
263 | * Frees the buffer allocated for crypto operation. | |
264 | */ | |
0b81d077 | 265 | void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str) |
6b3bd08f JK |
266 | { |
267 | if (!crypto_str) | |
268 | return; | |
269 | kfree(crypto_str->name); | |
270 | crypto_str->name = NULL; | |
271 | } | |
0b81d077 | 272 | EXPORT_SYMBOL(fscrypt_fname_free_buffer); |
6b3bd08f JK |
273 | |
274 | /** | |
0b81d077 JK |
275 | * fscrypt_fname_disk_to_usr() - converts a filename from disk space to user |
276 | * space | |
ef1eb3aa EB |
277 | * |
278 | * The caller must have allocated sufficient memory for the @oname string. | |
279 | * | |
280 | * Return: 0 on success, -errno on failure | |
6b3bd08f | 281 | */ |
0b81d077 JK |
282 | int fscrypt_fname_disk_to_usr(struct inode *inode, |
283 | u32 hash, u32 minor_hash, | |
284 | const struct fscrypt_str *iname, | |
285 | struct fscrypt_str *oname) | |
6b3bd08f JK |
286 | { |
287 | const struct qstr qname = FSTR_TO_QSTR(iname); | |
288 | char buf[24]; | |
6b3bd08f | 289 | |
0b81d077 | 290 | if (fscrypt_is_dot_dotdot(&qname)) { |
6b3bd08f JK |
291 | oname->name[0] = '.'; |
292 | oname->name[iname->len - 1] = '.'; | |
293 | oname->len = iname->len; | |
ef1eb3aa | 294 | return 0; |
6b3bd08f JK |
295 | } |
296 | ||
0b81d077 | 297 | if (iname->len < FS_CRYPTO_BLOCK_SIZE) |
1dafa51d | 298 | return -EUCLEAN; |
6b3bd08f | 299 | |
0b81d077 JK |
300 | if (inode->i_crypt_info) |
301 | return fname_decrypt(inode, iname, oname); | |
302 | ||
303 | if (iname->len <= FS_FNAME_CRYPTO_DIGEST_SIZE) { | |
ef1eb3aa EB |
304 | oname->len = digest_encode(iname->name, iname->len, |
305 | oname->name); | |
306 | return 0; | |
6b3bd08f JK |
307 | } |
308 | if (hash) { | |
0b81d077 JK |
309 | memcpy(buf, &hash, 4); |
310 | memcpy(buf + 4, &minor_hash, 4); | |
311 | } else { | |
6b3bd08f | 312 | memset(buf, 0, 8); |
0b81d077 | 313 | } |
6b3bd08f JK |
314 | memcpy(buf + 8, iname->name + iname->len - 16, 16); |
315 | oname->name[0] = '_'; | |
ef1eb3aa EB |
316 | oname->len = 1 + digest_encode(buf, 24, oname->name + 1); |
317 | return 0; | |
6b3bd08f | 318 | } |
0b81d077 | 319 | EXPORT_SYMBOL(fscrypt_fname_disk_to_usr); |
6b3bd08f JK |
320 | |
321 | /** | |
0b81d077 JK |
322 | * fscrypt_fname_usr_to_disk() - converts a filename from user space to disk |
323 | * space | |
ef1eb3aa EB |
324 | * |
325 | * The caller must have allocated sufficient memory for the @oname string. | |
326 | * | |
327 | * Return: 0 on success, -errno on failure | |
6b3bd08f | 328 | */ |
0b81d077 | 329 | int fscrypt_fname_usr_to_disk(struct inode *inode, |
6b3bd08f | 330 | const struct qstr *iname, |
0b81d077 | 331 | struct fscrypt_str *oname) |
6b3bd08f | 332 | { |
0b81d077 | 333 | if (fscrypt_is_dot_dotdot(iname)) { |
6b3bd08f JK |
334 | oname->name[0] = '.'; |
335 | oname->name[iname->len - 1] = '.'; | |
336 | oname->len = iname->len; | |
ef1eb3aa | 337 | return 0; |
6b3bd08f | 338 | } |
0b81d077 JK |
339 | if (inode->i_crypt_info) |
340 | return fname_encrypt(inode, iname, oname); | |
341 | /* | |
342 | * Without a proper key, a user is not allowed to modify the filenames | |
6b3bd08f | 343 | * in a directory. Consequently, a user space name cannot be mapped to |
0b81d077 JK |
344 | * a disk-space name |
345 | */ | |
6b3bd08f JK |
346 | return -EACCES; |
347 | } | |
0b81d077 | 348 | EXPORT_SYMBOL(fscrypt_fname_usr_to_disk); |
6b3bd08f | 349 | |
0b81d077 JK |
350 | int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, |
351 | int lookup, struct fscrypt_name *fname) | |
6b3bd08f | 352 | { |
6b3bd08f JK |
353 | int ret = 0, bigname = 0; |
354 | ||
0b81d077 | 355 | memset(fname, 0, sizeof(struct fscrypt_name)); |
6b3bd08f JK |
356 | fname->usr_fname = iname; |
357 | ||
0b81d077 JK |
358 | if (!dir->i_sb->s_cop->is_encrypted(dir) || |
359 | fscrypt_is_dot_dotdot(iname)) { | |
6b3bd08f JK |
360 | fname->disk_name.name = (unsigned char *)iname->name; |
361 | fname->disk_name.len = iname->len; | |
7bf4b557 | 362 | return 0; |
6b3bd08f | 363 | } |
0b81d077 JK |
364 | ret = get_crypt_info(dir); |
365 | if (ret && ret != -EOPNOTSUPP) | |
6b3bd08f | 366 | return ret; |
0b81d077 JK |
367 | |
368 | if (dir->i_crypt_info) { | |
369 | ret = fscrypt_fname_alloc_buffer(dir, iname->len, | |
370 | &fname->crypto_buf); | |
ef1eb3aa | 371 | if (ret) |
7bf4b557 | 372 | return ret; |
0b81d077 | 373 | ret = fname_encrypt(dir, iname, &fname->crypto_buf); |
ef1eb3aa | 374 | if (ret) |
e5e0906b | 375 | goto errout; |
6b3bd08f JK |
376 | fname->disk_name.name = fname->crypto_buf.name; |
377 | fname->disk_name.len = fname->crypto_buf.len; | |
7bf4b557 | 378 | return 0; |
6b3bd08f | 379 | } |
e5e0906b JK |
380 | if (!lookup) |
381 | return -EACCES; | |
6b3bd08f | 382 | |
0b81d077 JK |
383 | /* |
384 | * We don't have the key and we are doing a lookup; decode the | |
6b3bd08f JK |
385 | * user-supplied name |
386 | */ | |
387 | if (iname->name[0] == '_') | |
388 | bigname = 1; | |
0b81d077 | 389 | if ((bigname && (iname->len != 33)) || (!bigname && (iname->len > 43))) |
e5e0906b JK |
390 | return -ENOENT; |
391 | ||
6b3bd08f | 392 | fname->crypto_buf.name = kmalloc(32, GFP_KERNEL); |
e5e0906b JK |
393 | if (fname->crypto_buf.name == NULL) |
394 | return -ENOMEM; | |
0b81d077 | 395 | |
6b3bd08f JK |
396 | ret = digest_decode(iname->name + bigname, iname->len - bigname, |
397 | fname->crypto_buf.name); | |
398 | if (ret < 0) { | |
399 | ret = -ENOENT; | |
e5e0906b | 400 | goto errout; |
6b3bd08f JK |
401 | } |
402 | fname->crypto_buf.len = ret; | |
403 | if (bigname) { | |
404 | memcpy(&fname->hash, fname->crypto_buf.name, 4); | |
0b81d077 | 405 | memcpy(&fname->minor_hash, fname->crypto_buf.name + 4, 4); |
6b3bd08f JK |
406 | } else { |
407 | fname->disk_name.name = fname->crypto_buf.name; | |
408 | fname->disk_name.len = fname->crypto_buf.len; | |
409 | } | |
7bf4b557 | 410 | return 0; |
0b81d077 | 411 | |
e5e0906b | 412 | errout: |
0b81d077 | 413 | fscrypt_fname_free_buffer(&fname->crypto_buf); |
6b3bd08f JK |
414 | return ret; |
415 | } | |
0b81d077 | 416 | EXPORT_SYMBOL(fscrypt_setup_filename); |
6b3bd08f | 417 | |
0b81d077 | 418 | void fscrypt_free_filename(struct fscrypt_name *fname) |
6b3bd08f JK |
419 | { |
420 | kfree(fname->crypto_buf.name); | |
421 | fname->crypto_buf.name = NULL; | |
422 | fname->usr_fname = NULL; | |
423 | fname->disk_name.name = NULL; | |
424 | } | |
0b81d077 | 425 | EXPORT_SYMBOL(fscrypt_free_filename); |