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Commit | Line | Data |
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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> |
3325bea5 | 15 | #include "fscrypt_private.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 | 41 | { |
2731a944 | 42 | struct skcipher_request *req = NULL; |
0b81d077 JK |
43 | DECLARE_FS_COMPLETION_RESULT(ecr); |
44 | struct fscrypt_info *ci = inode->i_crypt_info; | |
2731a944 | 45 | struct crypto_skcipher *tfm = ci->ci_ctfm; |
6b3bd08f | 46 | int res = 0; |
0b81d077 | 47 | char iv[FS_CRYPTO_BLOCK_SIZE]; |
08ae877f | 48 | struct scatterlist sg; |
0b81d077 | 49 | int padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK); |
08ae877f EB |
50 | unsigned int lim; |
51 | unsigned int cryptlen; | |
6b3bd08f | 52 | |
0b81d077 | 53 | lim = inode->i_sb->s_cop->max_namelen(inode); |
6b3bd08f JK |
54 | if (iname->len <= 0 || iname->len > lim) |
55 | return -EIO; | |
56 | ||
08ae877f EB |
57 | /* |
58 | * Copy the filename to the output buffer for encrypting in-place and | |
59 | * pad it with the needed number of NUL bytes. | |
60 | */ | |
61 | cryptlen = max_t(unsigned int, iname->len, FS_CRYPTO_BLOCK_SIZE); | |
62 | cryptlen = round_up(cryptlen, padding); | |
63 | cryptlen = min(cryptlen, lim); | |
64 | memcpy(oname->name, iname->name, iname->len); | |
65 | memset(oname->name + iname->len, 0, cryptlen - iname->len); | |
6b3bd08f | 66 | |
08ae877f EB |
67 | /* Initialize the IV */ |
68 | memset(iv, 0, FS_CRYPTO_BLOCK_SIZE); | |
6b3bd08f | 69 | |
08ae877f | 70 | /* Set up the encryption request */ |
2731a944 | 71 | req = skcipher_request_alloc(tfm, GFP_NOFS); |
6b3bd08f JK |
72 | if (!req) { |
73 | printk_ratelimited(KERN_ERR | |
08ae877f | 74 | "%s: skcipher_request_alloc() failed\n", __func__); |
6b3bd08f JK |
75 | return -ENOMEM; |
76 | } | |
2731a944 | 77 | skcipher_request_set_callback(req, |
6b3bd08f | 78 | CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, |
53fd7550 | 79 | fname_crypt_complete, &ecr); |
08ae877f EB |
80 | sg_init_one(&sg, oname->name, cryptlen); |
81 | skcipher_request_set_crypt(req, &sg, &sg, cryptlen, iv); | |
6b3bd08f | 82 | |
08ae877f | 83 | /* Do the encryption */ |
2731a944 | 84 | res = crypto_skcipher_encrypt(req); |
6b3bd08f | 85 | if (res == -EINPROGRESS || res == -EBUSY) { |
08ae877f | 86 | /* Request is being completed asynchronously; wait for it */ |
6b3bd08f JK |
87 | wait_for_completion(&ecr.completion); |
88 | res = ecr.res; | |
89 | } | |
2731a944 | 90 | skcipher_request_free(req); |
ef1eb3aa | 91 | if (res < 0) { |
6b3bd08f JK |
92 | printk_ratelimited(KERN_ERR |
93 | "%s: Error (error code %d)\n", __func__, res); | |
ef1eb3aa EB |
94 | return res; |
95 | } | |
0b81d077 | 96 | |
08ae877f | 97 | oname->len = cryptlen; |
ef1eb3aa | 98 | return 0; |
6b3bd08f JK |
99 | } |
100 | ||
ef1eb3aa EB |
101 | /** |
102 | * fname_decrypt() - decrypt a filename | |
103 | * | |
104 | * The caller must have allocated sufficient memory for the @oname string. | |
105 | * | |
106 | * Return: 0 on success, -errno on failure | |
6b3bd08f | 107 | */ |
0b81d077 JK |
108 | static int fname_decrypt(struct inode *inode, |
109 | const struct fscrypt_str *iname, | |
110 | struct fscrypt_str *oname) | |
6b3bd08f | 111 | { |
2731a944 | 112 | struct skcipher_request *req = NULL; |
0b81d077 | 113 | DECLARE_FS_COMPLETION_RESULT(ecr); |
6b3bd08f | 114 | struct scatterlist src_sg, dst_sg; |
0b81d077 | 115 | struct fscrypt_info *ci = inode->i_crypt_info; |
2731a944 | 116 | struct crypto_skcipher *tfm = ci->ci_ctfm; |
6b3bd08f | 117 | int res = 0; |
0b81d077 JK |
118 | char iv[FS_CRYPTO_BLOCK_SIZE]; |
119 | unsigned lim; | |
6b3bd08f | 120 | |
0b81d077 | 121 | lim = inode->i_sb->s_cop->max_namelen(inode); |
6b3bd08f JK |
122 | if (iname->len <= 0 || iname->len > lim) |
123 | return -EIO; | |
124 | ||
125 | /* Allocate request */ | |
2731a944 | 126 | req = skcipher_request_alloc(tfm, GFP_NOFS); |
6b3bd08f JK |
127 | if (!req) { |
128 | printk_ratelimited(KERN_ERR | |
129 | "%s: crypto_request_alloc() failed\n", __func__); | |
130 | return -ENOMEM; | |
131 | } | |
2731a944 | 132 | skcipher_request_set_callback(req, |
6b3bd08f | 133 | CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, |
53fd7550 | 134 | fname_crypt_complete, &ecr); |
6b3bd08f JK |
135 | |
136 | /* Initialize IV */ | |
0b81d077 | 137 | memset(iv, 0, FS_CRYPTO_BLOCK_SIZE); |
6b3bd08f JK |
138 | |
139 | /* Create decryption request */ | |
140 | sg_init_one(&src_sg, iname->name, iname->len); | |
141 | sg_init_one(&dst_sg, oname->name, oname->len); | |
2731a944 HX |
142 | skcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, iv); |
143 | res = crypto_skcipher_decrypt(req); | |
6b3bd08f | 144 | if (res == -EINPROGRESS || res == -EBUSY) { |
6b3bd08f JK |
145 | wait_for_completion(&ecr.completion); |
146 | res = ecr.res; | |
147 | } | |
2731a944 | 148 | skcipher_request_free(req); |
6b3bd08f JK |
149 | if (res < 0) { |
150 | printk_ratelimited(KERN_ERR | |
0b81d077 | 151 | "%s: Error (error code %d)\n", __func__, res); |
6b3bd08f JK |
152 | return res; |
153 | } | |
154 | ||
155 | oname->len = strnlen(oname->name, iname->len); | |
ef1eb3aa | 156 | return 0; |
6b3bd08f JK |
157 | } |
158 | ||
159 | static const char *lookup_table = | |
160 | "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,"; | |
161 | ||
162 | /** | |
0b81d077 | 163 | * digest_encode() - |
6b3bd08f JK |
164 | * |
165 | * Encodes the input digest using characters from the set [a-zA-Z0-9_+]. | |
166 | * The encoded string is roughly 4/3 times the size of the input string. | |
167 | */ | |
168 | static int digest_encode(const char *src, int len, char *dst) | |
169 | { | |
170 | int i = 0, bits = 0, ac = 0; | |
171 | char *cp = dst; | |
172 | ||
173 | while (i < len) { | |
174 | ac += (((unsigned char) src[i]) << bits); | |
175 | bits += 8; | |
176 | do { | |
177 | *cp++ = lookup_table[ac & 0x3f]; | |
178 | ac >>= 6; | |
179 | bits -= 6; | |
180 | } while (bits >= 6); | |
181 | i++; | |
182 | } | |
183 | if (bits) | |
184 | *cp++ = lookup_table[ac & 0x3f]; | |
185 | return cp - dst; | |
186 | } | |
187 | ||
188 | static int digest_decode(const char *src, int len, char *dst) | |
189 | { | |
190 | int i = 0, bits = 0, ac = 0; | |
191 | const char *p; | |
192 | char *cp = dst; | |
193 | ||
194 | while (i < len) { | |
195 | p = strchr(lookup_table, src[i]); | |
196 | if (p == NULL || src[i] == 0) | |
197 | return -2; | |
198 | ac += (p - lookup_table) << bits; | |
199 | bits += 6; | |
200 | if (bits >= 8) { | |
201 | *cp++ = ac & 0xff; | |
202 | ac >>= 8; | |
203 | bits -= 8; | |
204 | } | |
205 | i++; | |
206 | } | |
207 | if (ac) | |
208 | return -1; | |
209 | return cp - dst; | |
210 | } | |
211 | ||
0b93e1b9 | 212 | u32 fscrypt_fname_encrypted_size(const struct inode *inode, u32 ilen) |
6b3bd08f | 213 | { |
922ec355 | 214 | int padding = 32; |
0b81d077 | 215 | struct fscrypt_info *ci = inode->i_crypt_info; |
922ec355 CY |
216 | |
217 | if (ci) | |
0b81d077 | 218 | padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK); |
55be3145 EB |
219 | ilen = max(ilen, (u32)FS_CRYPTO_BLOCK_SIZE); |
220 | return round_up(ilen, padding); | |
6b3bd08f | 221 | } |
0b81d077 | 222 | EXPORT_SYMBOL(fscrypt_fname_encrypted_size); |
6b3bd08f JK |
223 | |
224 | /** | |
0b81d077 | 225 | * fscrypt_fname_crypto_alloc_obuff() - |
6b3bd08f JK |
226 | * |
227 | * Allocates an output buffer that is sufficient for the crypto operation | |
228 | * specified by the context and the direction. | |
229 | */ | |
0b93e1b9 | 230 | int fscrypt_fname_alloc_buffer(const struct inode *inode, |
0b81d077 | 231 | u32 ilen, struct fscrypt_str *crypto_str) |
6b3bd08f | 232 | { |
0b81d077 | 233 | unsigned int olen = fscrypt_fname_encrypted_size(inode, ilen); |
6b3bd08f | 234 | |
6b3bd08f | 235 | crypto_str->len = olen; |
0b81d077 JK |
236 | if (olen < FS_FNAME_CRYPTO_DIGEST_SIZE * 2) |
237 | olen = FS_FNAME_CRYPTO_DIGEST_SIZE * 2; | |
238 | /* | |
239 | * Allocated buffer can hold one more character to null-terminate the | |
240 | * string | |
241 | */ | |
6b3bd08f JK |
242 | crypto_str->name = kmalloc(olen + 1, GFP_NOFS); |
243 | if (!(crypto_str->name)) | |
244 | return -ENOMEM; | |
245 | return 0; | |
246 | } | |
0b81d077 | 247 | EXPORT_SYMBOL(fscrypt_fname_alloc_buffer); |
6b3bd08f JK |
248 | |
249 | /** | |
0b81d077 | 250 | * fscrypt_fname_crypto_free_buffer() - |
6b3bd08f JK |
251 | * |
252 | * Frees the buffer allocated for crypto operation. | |
253 | */ | |
0b81d077 | 254 | void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str) |
6b3bd08f JK |
255 | { |
256 | if (!crypto_str) | |
257 | return; | |
258 | kfree(crypto_str->name); | |
259 | crypto_str->name = NULL; | |
260 | } | |
0b81d077 | 261 | EXPORT_SYMBOL(fscrypt_fname_free_buffer); |
6b3bd08f JK |
262 | |
263 | /** | |
0b81d077 JK |
264 | * fscrypt_fname_disk_to_usr() - converts a filename from disk space to user |
265 | * space | |
ef1eb3aa EB |
266 | * |
267 | * The caller must have allocated sufficient memory for the @oname string. | |
268 | * | |
269 | * Return: 0 on success, -errno on failure | |
6b3bd08f | 270 | */ |
0b81d077 JK |
271 | int fscrypt_fname_disk_to_usr(struct inode *inode, |
272 | u32 hash, u32 minor_hash, | |
273 | const struct fscrypt_str *iname, | |
274 | struct fscrypt_str *oname) | |
6b3bd08f JK |
275 | { |
276 | const struct qstr qname = FSTR_TO_QSTR(iname); | |
277 | char buf[24]; | |
6b3bd08f | 278 | |
0b81d077 | 279 | if (fscrypt_is_dot_dotdot(&qname)) { |
6b3bd08f JK |
280 | oname->name[0] = '.'; |
281 | oname->name[iname->len - 1] = '.'; | |
282 | oname->len = iname->len; | |
ef1eb3aa | 283 | return 0; |
6b3bd08f JK |
284 | } |
285 | ||
0b81d077 | 286 | if (iname->len < FS_CRYPTO_BLOCK_SIZE) |
1dafa51d | 287 | return -EUCLEAN; |
6b3bd08f | 288 | |
0b81d077 JK |
289 | if (inode->i_crypt_info) |
290 | return fname_decrypt(inode, iname, oname); | |
291 | ||
292 | if (iname->len <= FS_FNAME_CRYPTO_DIGEST_SIZE) { | |
ef1eb3aa EB |
293 | oname->len = digest_encode(iname->name, iname->len, |
294 | oname->name); | |
295 | return 0; | |
6b3bd08f JK |
296 | } |
297 | if (hash) { | |
0b81d077 JK |
298 | memcpy(buf, &hash, 4); |
299 | memcpy(buf + 4, &minor_hash, 4); | |
300 | } else { | |
6b3bd08f | 301 | memset(buf, 0, 8); |
0b81d077 | 302 | } |
6b3bd08f JK |
303 | memcpy(buf + 8, iname->name + iname->len - 16, 16); |
304 | oname->name[0] = '_'; | |
ef1eb3aa EB |
305 | oname->len = 1 + digest_encode(buf, 24, oname->name + 1); |
306 | return 0; | |
6b3bd08f | 307 | } |
0b81d077 | 308 | EXPORT_SYMBOL(fscrypt_fname_disk_to_usr); |
6b3bd08f JK |
309 | |
310 | /** | |
0b81d077 JK |
311 | * fscrypt_fname_usr_to_disk() - converts a filename from user space to disk |
312 | * space | |
ef1eb3aa EB |
313 | * |
314 | * The caller must have allocated sufficient memory for the @oname string. | |
315 | * | |
316 | * Return: 0 on success, -errno on failure | |
6b3bd08f | 317 | */ |
0b81d077 | 318 | int fscrypt_fname_usr_to_disk(struct inode *inode, |
6b3bd08f | 319 | const struct qstr *iname, |
0b81d077 | 320 | struct fscrypt_str *oname) |
6b3bd08f | 321 | { |
0b81d077 | 322 | if (fscrypt_is_dot_dotdot(iname)) { |
6b3bd08f JK |
323 | oname->name[0] = '.'; |
324 | oname->name[iname->len - 1] = '.'; | |
325 | oname->len = iname->len; | |
ef1eb3aa | 326 | return 0; |
6b3bd08f | 327 | } |
0b81d077 JK |
328 | if (inode->i_crypt_info) |
329 | return fname_encrypt(inode, iname, oname); | |
330 | /* | |
331 | * Without a proper key, a user is not allowed to modify the filenames | |
6b3bd08f | 332 | * in a directory. Consequently, a user space name cannot be mapped to |
0b81d077 JK |
333 | * a disk-space name |
334 | */ | |
6b3bd08f JK |
335 | return -EACCES; |
336 | } | |
0b81d077 | 337 | EXPORT_SYMBOL(fscrypt_fname_usr_to_disk); |
6b3bd08f | 338 | |
0b81d077 JK |
339 | int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, |
340 | int lookup, struct fscrypt_name *fname) | |
6b3bd08f | 341 | { |
6b3bd08f JK |
342 | int ret = 0, bigname = 0; |
343 | ||
0b81d077 | 344 | memset(fname, 0, sizeof(struct fscrypt_name)); |
6b3bd08f JK |
345 | fname->usr_fname = iname; |
346 | ||
0b81d077 JK |
347 | if (!dir->i_sb->s_cop->is_encrypted(dir) || |
348 | fscrypt_is_dot_dotdot(iname)) { | |
6b3bd08f JK |
349 | fname->disk_name.name = (unsigned char *)iname->name; |
350 | fname->disk_name.len = iname->len; | |
7bf4b557 | 351 | return 0; |
6b3bd08f | 352 | } |
3325bea5 | 353 | ret = fscrypt_get_crypt_info(dir); |
0b81d077 | 354 | if (ret && ret != -EOPNOTSUPP) |
6b3bd08f | 355 | return ret; |
0b81d077 JK |
356 | |
357 | if (dir->i_crypt_info) { | |
358 | ret = fscrypt_fname_alloc_buffer(dir, iname->len, | |
359 | &fname->crypto_buf); | |
ef1eb3aa | 360 | if (ret) |
7bf4b557 | 361 | return ret; |
0b81d077 | 362 | ret = fname_encrypt(dir, iname, &fname->crypto_buf); |
ef1eb3aa | 363 | if (ret) |
e5e0906b | 364 | goto errout; |
6b3bd08f JK |
365 | fname->disk_name.name = fname->crypto_buf.name; |
366 | fname->disk_name.len = fname->crypto_buf.len; | |
7bf4b557 | 367 | return 0; |
6b3bd08f | 368 | } |
e5e0906b JK |
369 | if (!lookup) |
370 | return -EACCES; | |
6b3bd08f | 371 | |
0b81d077 JK |
372 | /* |
373 | * We don't have the key and we are doing a lookup; decode the | |
6b3bd08f JK |
374 | * user-supplied name |
375 | */ | |
376 | if (iname->name[0] == '_') | |
377 | bigname = 1; | |
0b81d077 | 378 | if ((bigname && (iname->len != 33)) || (!bigname && (iname->len > 43))) |
e5e0906b JK |
379 | return -ENOENT; |
380 | ||
6b3bd08f | 381 | fname->crypto_buf.name = kmalloc(32, GFP_KERNEL); |
e5e0906b JK |
382 | if (fname->crypto_buf.name == NULL) |
383 | return -ENOMEM; | |
0b81d077 | 384 | |
6b3bd08f JK |
385 | ret = digest_decode(iname->name + bigname, iname->len - bigname, |
386 | fname->crypto_buf.name); | |
387 | if (ret < 0) { | |
388 | ret = -ENOENT; | |
e5e0906b | 389 | goto errout; |
6b3bd08f JK |
390 | } |
391 | fname->crypto_buf.len = ret; | |
392 | if (bigname) { | |
393 | memcpy(&fname->hash, fname->crypto_buf.name, 4); | |
0b81d077 | 394 | memcpy(&fname->minor_hash, fname->crypto_buf.name + 4, 4); |
6b3bd08f JK |
395 | } else { |
396 | fname->disk_name.name = fname->crypto_buf.name; | |
397 | fname->disk_name.len = fname->crypto_buf.len; | |
398 | } | |
7bf4b557 | 399 | return 0; |
0b81d077 | 400 | |
e5e0906b | 401 | errout: |
0b81d077 | 402 | fscrypt_fname_free_buffer(&fname->crypto_buf); |
6b3bd08f JK |
403 | return ret; |
404 | } | |
0b81d077 | 405 | EXPORT_SYMBOL(fscrypt_setup_filename); |
6b3bd08f | 406 | |
0b81d077 | 407 | void fscrypt_free_filename(struct fscrypt_name *fname) |
6b3bd08f JK |
408 | { |
409 | kfree(fname->crypto_buf.name); | |
410 | fname->crypto_buf.name = NULL; | |
411 | fname->usr_fname = NULL; | |
412 | fname->disk_name.name = NULL; | |
413 | } | |
0b81d077 | 414 | EXPORT_SYMBOL(fscrypt_free_filename); |