Commit | Line | Data |
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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
0b81d077 JK |
2 | /* |
3 | * Encryption policy functions for per-file encryption support. | |
4 | * | |
5 | * Copyright (C) 2015, Google, Inc. | |
6 | * Copyright (C) 2015, Motorola Mobility. | |
7 | * | |
5dae460c | 8 | * Originally written by Michael Halcrow, 2015. |
0b81d077 | 9 | * Modified by Jaegeuk Kim, 2015. |
5dae460c | 10 | * Modified by Eric Biggers, 2019 for v2 policy support. |
0b81d077 JK |
11 | */ |
12 | ||
218d921b | 13 | #include <linux/fs_context.h> |
0b81d077 | 14 | #include <linux/random.h> |
ed318a6c | 15 | #include <linux/seq_file.h> |
0b81d077 | 16 | #include <linux/string.h> |
ba63f23d | 17 | #include <linux/mount.h> |
cc4e0df0 | 18 | #include "fscrypt_private.h" |
0b81d077 | 19 | |
5dae460c | 20 | /** |
d2fe9754 EB |
21 | * fscrypt_policies_equal() - check whether two encryption policies are the same |
22 | * @policy1: the first policy | |
23 | * @policy2: the second policy | |
5dae460c EB |
24 | * |
25 | * Return: %true if equal, else %false | |
0b81d077 | 26 | */ |
5dae460c EB |
27 | bool fscrypt_policies_equal(const union fscrypt_policy *policy1, |
28 | const union fscrypt_policy *policy2) | |
0b81d077 | 29 | { |
5dae460c EB |
30 | if (policy1->version != policy2->version) |
31 | return false; | |
32 | ||
33 | return !memcmp(policy1, policy2, fscrypt_policy_size(policy1)); | |
0b81d077 JK |
34 | } |
35 | ||
bfb9700b EB |
36 | int fscrypt_policy_to_key_spec(const union fscrypt_policy *policy, |
37 | struct fscrypt_key_specifier *key_spec) | |
38 | { | |
39 | switch (policy->version) { | |
40 | case FSCRYPT_POLICY_V1: | |
41 | key_spec->type = FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR; | |
42 | memcpy(key_spec->u.descriptor, policy->v1.master_key_descriptor, | |
43 | FSCRYPT_KEY_DESCRIPTOR_SIZE); | |
44 | return 0; | |
45 | case FSCRYPT_POLICY_V2: | |
46 | key_spec->type = FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER; | |
47 | memcpy(key_spec->u.identifier, policy->v2.master_key_identifier, | |
48 | FSCRYPT_KEY_IDENTIFIER_SIZE); | |
49 | return 0; | |
50 | default: | |
51 | WARN_ON(1); | |
52 | return -EINVAL; | |
53 | } | |
54 | } | |
55 | ||
ac4acb1f EB |
56 | static const union fscrypt_policy * |
57 | fscrypt_get_dummy_policy(struct super_block *sb) | |
58 | { | |
59 | if (!sb->s_cop->get_dummy_policy) | |
60 | return NULL; | |
61 | return sb->s_cop->get_dummy_policy(sb); | |
62 | } | |
63 | ||
6b2a51ff | 64 | static bool fscrypt_valid_enc_modes_v1(u32 contents_mode, u32 filenames_mode) |
ef5b18b0 EB |
65 | { |
66 | if (contents_mode == FSCRYPT_MODE_AES_256_XTS && | |
67 | filenames_mode == FSCRYPT_MODE_AES_256_CTS) | |
68 | return true; | |
69 | ||
70 | if (contents_mode == FSCRYPT_MODE_AES_128_CBC && | |
71 | filenames_mode == FSCRYPT_MODE_AES_128_CTS) | |
72 | return true; | |
73 | ||
74 | if (contents_mode == FSCRYPT_MODE_ADIANTUM && | |
75 | filenames_mode == FSCRYPT_MODE_ADIANTUM) | |
76 | return true; | |
77 | ||
78 | return false; | |
79 | } | |
80 | ||
6b2a51ff NH |
81 | static bool fscrypt_valid_enc_modes_v2(u32 contents_mode, u32 filenames_mode) |
82 | { | |
83 | if (contents_mode == FSCRYPT_MODE_AES_256_XTS && | |
84 | filenames_mode == FSCRYPT_MODE_AES_256_HCTR2) | |
85 | return true; | |
86 | return fscrypt_valid_enc_modes_v1(contents_mode, filenames_mode); | |
87 | } | |
88 | ||
85af90e5 EB |
89 | static bool supported_direct_key_modes(const struct inode *inode, |
90 | u32 contents_mode, u32 filenames_mode) | |
91 | { | |
92 | const struct fscrypt_mode *mode; | |
93 | ||
94 | if (contents_mode != filenames_mode) { | |
95 | fscrypt_warn(inode, | |
96 | "Direct key flag not allowed with different contents and filenames modes"); | |
97 | return false; | |
98 | } | |
99 | mode = &fscrypt_modes[contents_mode]; | |
100 | ||
101 | if (mode->ivsize < offsetofend(union fscrypt_iv, nonce)) { | |
102 | fscrypt_warn(inode, "Direct key flag not allowed with %s", | |
103 | mode->friendly_name); | |
104 | return false; | |
105 | } | |
106 | return true; | |
107 | } | |
108 | ||
e3b1078b EB |
109 | static bool supported_iv_ino_lblk_policy(const struct fscrypt_policy_v2 *policy, |
110 | const struct inode *inode, | |
111 | const char *type, | |
112 | int max_ino_bits, int max_lblk_bits) | |
b103fb76 EB |
113 | { |
114 | struct super_block *sb = inode->i_sb; | |
115 | int ino_bits = 64, lblk_bits = 64; | |
116 | ||
f000223c EB |
117 | /* |
118 | * IV_INO_LBLK_* exist only because of hardware limitations, and | |
119 | * currently the only known use case for them involves AES-256-XTS. | |
120 | * That's also all we test currently. For these reasons, for now only | |
121 | * allow AES-256-XTS here. This can be relaxed later if a use case for | |
122 | * IV_INO_LBLK_* with other encryption modes arises. | |
123 | */ | |
124 | if (policy->contents_encryption_mode != FSCRYPT_MODE_AES_256_XTS) { | |
125 | fscrypt_warn(inode, | |
126 | "Can't use %s policy with contents mode other than AES-256-XTS", | |
127 | type); | |
128 | return false; | |
129 | } | |
130 | ||
b103fb76 EB |
131 | /* |
132 | * It's unsafe to include inode numbers in the IVs if the filesystem can | |
133 | * potentially renumber inodes, e.g. via filesystem shrinking. | |
134 | */ | |
135 | if (!sb->s_cop->has_stable_inodes || | |
136 | !sb->s_cop->has_stable_inodes(sb)) { | |
137 | fscrypt_warn(inode, | |
e3b1078b EB |
138 | "Can't use %s policy on filesystem '%s' because it doesn't have stable inode numbers", |
139 | type, sb->s_id); | |
b103fb76 EB |
140 | return false; |
141 | } | |
142 | if (sb->s_cop->get_ino_and_lblk_bits) | |
143 | sb->s_cop->get_ino_and_lblk_bits(sb, &ino_bits, &lblk_bits); | |
e3b1078b EB |
144 | if (ino_bits > max_ino_bits) { |
145 | fscrypt_warn(inode, | |
146 | "Can't use %s policy on filesystem '%s' because its inode numbers are too long", | |
147 | type, sb->s_id); | |
148 | return false; | |
149 | } | |
150 | if (lblk_bits > max_lblk_bits) { | |
b103fb76 | 151 | fscrypt_warn(inode, |
e3b1078b EB |
152 | "Can't use %s policy on filesystem '%s' because its block numbers are too long", |
153 | type, sb->s_id); | |
b103fb76 EB |
154 | return false; |
155 | } | |
156 | return true; | |
157 | } | |
158 | ||
393a24a7 EB |
159 | static bool fscrypt_supported_v1_policy(const struct fscrypt_policy_v1 *policy, |
160 | const struct inode *inode) | |
161 | { | |
6b2a51ff | 162 | if (!fscrypt_valid_enc_modes_v1(policy->contents_encryption_mode, |
393a24a7 EB |
163 | policy->filenames_encryption_mode)) { |
164 | fscrypt_warn(inode, | |
165 | "Unsupported encryption modes (contents %d, filenames %d)", | |
166 | policy->contents_encryption_mode, | |
167 | policy->filenames_encryption_mode); | |
168 | return false; | |
169 | } | |
170 | ||
171 | if (policy->flags & ~(FSCRYPT_POLICY_FLAGS_PAD_MASK | | |
172 | FSCRYPT_POLICY_FLAG_DIRECT_KEY)) { | |
173 | fscrypt_warn(inode, "Unsupported encryption flags (0x%02x)", | |
174 | policy->flags); | |
175 | return false; | |
176 | } | |
177 | ||
85af90e5 EB |
178 | if ((policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) && |
179 | !supported_direct_key_modes(inode, policy->contents_encryption_mode, | |
180 | policy->filenames_encryption_mode)) | |
181 | return false; | |
182 | ||
6e1918cf DR |
183 | if (IS_CASEFOLDED(inode)) { |
184 | /* With v1, there's no way to derive dirhash keys. */ | |
185 | fscrypt_warn(inode, | |
186 | "v1 policies can't be used on casefolded directories"); | |
187 | return false; | |
188 | } | |
189 | ||
393a24a7 EB |
190 | return true; |
191 | } | |
192 | ||
193 | static bool fscrypt_supported_v2_policy(const struct fscrypt_policy_v2 *policy, | |
194 | const struct inode *inode) | |
195 | { | |
e3b1078b EB |
196 | int count = 0; |
197 | ||
6b2a51ff | 198 | if (!fscrypt_valid_enc_modes_v2(policy->contents_encryption_mode, |
393a24a7 EB |
199 | policy->filenames_encryption_mode)) { |
200 | fscrypt_warn(inode, | |
201 | "Unsupported encryption modes (contents %d, filenames %d)", | |
202 | policy->contents_encryption_mode, | |
203 | policy->filenames_encryption_mode); | |
204 | return false; | |
205 | } | |
206 | ||
3ceb6543 EB |
207 | if (policy->flags & ~(FSCRYPT_POLICY_FLAGS_PAD_MASK | |
208 | FSCRYPT_POLICY_FLAG_DIRECT_KEY | | |
209 | FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64 | | |
210 | FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) { | |
393a24a7 EB |
211 | fscrypt_warn(inode, "Unsupported encryption flags (0x%02x)", |
212 | policy->flags); | |
213 | return false; | |
214 | } | |
215 | ||
e3b1078b EB |
216 | count += !!(policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY); |
217 | count += !!(policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64); | |
218 | count += !!(policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32); | |
219 | if (count > 1) { | |
220 | fscrypt_warn(inode, "Mutually exclusive encryption flags (0x%02x)", | |
221 | policy->flags); | |
222 | return false; | |
223 | } | |
224 | ||
85af90e5 EB |
225 | if ((policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) && |
226 | !supported_direct_key_modes(inode, policy->contents_encryption_mode, | |
227 | policy->filenames_encryption_mode)) | |
228 | return false; | |
229 | ||
393a24a7 | 230 | if ((policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) && |
e3b1078b EB |
231 | !supported_iv_ino_lblk_policy(policy, inode, "IV_INO_LBLK_64", |
232 | 32, 32)) | |
233 | return false; | |
234 | ||
5e895bd4 EB |
235 | /* |
236 | * IV_INO_LBLK_32 hashes the inode number, so in principle it can | |
237 | * support any ino_bits. However, currently the inode number is gotten | |
238 | * from inode::i_ino which is 'unsigned long'. So for now the | |
239 | * implementation limit is 32 bits. | |
240 | */ | |
e3b1078b | 241 | if ((policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) && |
e3b1078b | 242 | !supported_iv_ino_lblk_policy(policy, inode, "IV_INO_LBLK_32", |
5e895bd4 | 243 | 32, 32)) |
393a24a7 EB |
244 | return false; |
245 | ||
246 | if (memchr_inv(policy->__reserved, 0, sizeof(policy->__reserved))) { | |
247 | fscrypt_warn(inode, "Reserved bits set in encryption policy"); | |
248 | return false; | |
249 | } | |
250 | ||
251 | return true; | |
252 | } | |
253 | ||
5dae460c | 254 | /** |
d2fe9754 EB |
255 | * fscrypt_supported_policy() - check whether an encryption policy is supported |
256 | * @policy_u: the encryption policy | |
257 | * @inode: the inode on which the policy will be used | |
5dae460c EB |
258 | * |
259 | * Given an encryption policy, check whether all its encryption modes and other | |
393a24a7 EB |
260 | * settings are supported by this kernel on the given inode. (But we don't |
261 | * currently don't check for crypto API support here, so attempting to use an | |
262 | * algorithm not configured into the crypto API will still fail later.) | |
5dae460c EB |
263 | * |
264 | * Return: %true if supported, else %false | |
265 | */ | |
266 | bool fscrypt_supported_policy(const union fscrypt_policy *policy_u, | |
267 | const struct inode *inode) | |
0b81d077 | 268 | { |
5dae460c | 269 | switch (policy_u->version) { |
393a24a7 EB |
270 | case FSCRYPT_POLICY_V1: |
271 | return fscrypt_supported_v1_policy(&policy_u->v1, inode); | |
272 | case FSCRYPT_POLICY_V2: | |
273 | return fscrypt_supported_v2_policy(&policy_u->v2, inode); | |
5dae460c EB |
274 | } |
275 | return false; | |
276 | } | |
277 | ||
278 | /** | |
a992b20c | 279 | * fscrypt_new_context() - create a new fscrypt_context |
d2fe9754 EB |
280 | * @ctx_u: output context |
281 | * @policy_u: input policy | |
a992b20c | 282 | * @nonce: nonce to use |
5dae460c EB |
283 | * |
284 | * Create an fscrypt_context for an inode that is being assigned the given | |
a992b20c | 285 | * encryption policy. @nonce must be a new random nonce. |
5dae460c EB |
286 | * |
287 | * Return: the size of the new context in bytes. | |
288 | */ | |
a992b20c EB |
289 | static int fscrypt_new_context(union fscrypt_context *ctx_u, |
290 | const union fscrypt_policy *policy_u, | |
291 | const u8 nonce[FSCRYPT_FILE_NONCE_SIZE]) | |
5dae460c EB |
292 | { |
293 | memset(ctx_u, 0, sizeof(*ctx_u)); | |
294 | ||
295 | switch (policy_u->version) { | |
296 | case FSCRYPT_POLICY_V1: { | |
297 | const struct fscrypt_policy_v1 *policy = &policy_u->v1; | |
298 | struct fscrypt_context_v1 *ctx = &ctx_u->v1; | |
299 | ||
300 | ctx->version = FSCRYPT_CONTEXT_V1; | |
301 | ctx->contents_encryption_mode = | |
302 | policy->contents_encryption_mode; | |
303 | ctx->filenames_encryption_mode = | |
304 | policy->filenames_encryption_mode; | |
305 | ctx->flags = policy->flags; | |
306 | memcpy(ctx->master_key_descriptor, | |
307 | policy->master_key_descriptor, | |
308 | sizeof(ctx->master_key_descriptor)); | |
a992b20c | 309 | memcpy(ctx->nonce, nonce, FSCRYPT_FILE_NONCE_SIZE); |
5dae460c EB |
310 | return sizeof(*ctx); |
311 | } | |
312 | case FSCRYPT_POLICY_V2: { | |
313 | const struct fscrypt_policy_v2 *policy = &policy_u->v2; | |
314 | struct fscrypt_context_v2 *ctx = &ctx_u->v2; | |
315 | ||
316 | ctx->version = FSCRYPT_CONTEXT_V2; | |
317 | ctx->contents_encryption_mode = | |
318 | policy->contents_encryption_mode; | |
319 | ctx->filenames_encryption_mode = | |
320 | policy->filenames_encryption_mode; | |
321 | ctx->flags = policy->flags; | |
322 | memcpy(ctx->master_key_identifier, | |
323 | policy->master_key_identifier, | |
324 | sizeof(ctx->master_key_identifier)); | |
a992b20c | 325 | memcpy(ctx->nonce, nonce, FSCRYPT_FILE_NONCE_SIZE); |
5dae460c EB |
326 | return sizeof(*ctx); |
327 | } | |
328 | } | |
329 | BUG(); | |
330 | } | |
0b81d077 | 331 | |
5dae460c | 332 | /** |
d2fe9754 EB |
333 | * fscrypt_policy_from_context() - convert an fscrypt_context to |
334 | * an fscrypt_policy | |
335 | * @policy_u: output policy | |
336 | * @ctx_u: input context | |
337 | * @ctx_size: size of input context in bytes | |
5dae460c EB |
338 | * |
339 | * Given an fscrypt_context, build the corresponding fscrypt_policy. | |
340 | * | |
341 | * Return: 0 on success, or -EINVAL if the fscrypt_context has an unrecognized | |
342 | * version number or size. | |
343 | * | |
344 | * This does *not* validate the settings within the policy itself, e.g. the | |
345 | * modes, flags, and reserved bits. Use fscrypt_supported_policy() for that. | |
346 | */ | |
347 | int fscrypt_policy_from_context(union fscrypt_policy *policy_u, | |
348 | const union fscrypt_context *ctx_u, | |
349 | int ctx_size) | |
350 | { | |
351 | memset(policy_u, 0, sizeof(*policy_u)); | |
0b81d077 | 352 | |
e98ad464 | 353 | if (!fscrypt_context_is_valid(ctx_u, ctx_size)) |
0b81d077 | 354 | return -EINVAL; |
0b81d077 | 355 | |
5dae460c EB |
356 | switch (ctx_u->version) { |
357 | case FSCRYPT_CONTEXT_V1: { | |
358 | const struct fscrypt_context_v1 *ctx = &ctx_u->v1; | |
359 | struct fscrypt_policy_v1 *policy = &policy_u->v1; | |
360 | ||
361 | policy->version = FSCRYPT_POLICY_V1; | |
362 | policy->contents_encryption_mode = | |
363 | ctx->contents_encryption_mode; | |
364 | policy->filenames_encryption_mode = | |
365 | ctx->filenames_encryption_mode; | |
366 | policy->flags = ctx->flags; | |
367 | memcpy(policy->master_key_descriptor, | |
368 | ctx->master_key_descriptor, | |
369 | sizeof(policy->master_key_descriptor)); | |
370 | return 0; | |
371 | } | |
372 | case FSCRYPT_CONTEXT_V2: { | |
373 | const struct fscrypt_context_v2 *ctx = &ctx_u->v2; | |
374 | struct fscrypt_policy_v2 *policy = &policy_u->v2; | |
375 | ||
376 | policy->version = FSCRYPT_POLICY_V2; | |
377 | policy->contents_encryption_mode = | |
378 | ctx->contents_encryption_mode; | |
379 | policy->filenames_encryption_mode = | |
380 | ctx->filenames_encryption_mode; | |
381 | policy->flags = ctx->flags; | |
382 | memcpy(policy->__reserved, ctx->__reserved, | |
383 | sizeof(policy->__reserved)); | |
384 | memcpy(policy->master_key_identifier, | |
385 | ctx->master_key_identifier, | |
386 | sizeof(policy->master_key_identifier)); | |
387 | return 0; | |
388 | } | |
389 | } | |
390 | /* unreachable */ | |
391 | return -EINVAL; | |
392 | } | |
393 | ||
394 | /* Retrieve an inode's encryption policy */ | |
395 | static int fscrypt_get_policy(struct inode *inode, union fscrypt_policy *policy) | |
396 | { | |
397 | const struct fscrypt_info *ci; | |
398 | union fscrypt_context ctx; | |
399 | int ret; | |
400 | ||
ab673b98 | 401 | ci = fscrypt_get_info(inode); |
5dae460c EB |
402 | if (ci) { |
403 | /* key available, use the cached policy */ | |
404 | *policy = ci->ci_policy; | |
405 | return 0; | |
406 | } | |
407 | ||
408 | if (!IS_ENCRYPTED(inode)) | |
409 | return -ENODATA; | |
410 | ||
411 | ret = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx)); | |
412 | if (ret < 0) | |
413 | return (ret == -ERANGE) ? -EINVAL : ret; | |
414 | ||
415 | return fscrypt_policy_from_context(policy, &ctx, ret); | |
416 | } | |
417 | ||
418 | static int set_encryption_policy(struct inode *inode, | |
419 | const union fscrypt_policy *policy) | |
420 | { | |
a992b20c | 421 | u8 nonce[FSCRYPT_FILE_NONCE_SIZE]; |
5dae460c EB |
422 | union fscrypt_context ctx; |
423 | int ctxsize; | |
5ab7189a | 424 | int err; |
5dae460c EB |
425 | |
426 | if (!fscrypt_supported_policy(policy, inode)) | |
0b81d077 JK |
427 | return -EINVAL; |
428 | ||
5ab7189a EB |
429 | switch (policy->version) { |
430 | case FSCRYPT_POLICY_V1: | |
5dae460c EB |
431 | /* |
432 | * The original encryption policy version provided no way of | |
433 | * verifying that the correct master key was supplied, which was | |
434 | * insecure in scenarios where multiple users have access to the | |
435 | * same encrypted files (even just read-only access). The new | |
436 | * encryption policy version fixes this and also implies use of | |
437 | * an improved key derivation function and allows non-root users | |
438 | * to securely remove keys. So as long as compatibility with | |
439 | * old kernels isn't required, it is recommended to use the new | |
440 | * policy version for all new encrypted directories. | |
441 | */ | |
442 | pr_warn_once("%s (pid %d) is setting deprecated v1 encryption policy; recommend upgrading to v2.\n", | |
443 | current->comm, current->pid); | |
5ab7189a EB |
444 | break; |
445 | case FSCRYPT_POLICY_V2: | |
446 | err = fscrypt_verify_key_added(inode->i_sb, | |
447 | policy->v2.master_key_identifier); | |
448 | if (err) | |
449 | return err; | |
e3b1078b EB |
450 | if (policy->v2.flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) |
451 | pr_warn_once("%s (pid %d) is setting an IV_INO_LBLK_32 encryption policy. This should only be used if there are certain hardware limitations.\n", | |
452 | current->comm, current->pid); | |
5ab7189a EB |
453 | break; |
454 | default: | |
455 | WARN_ON(1); | |
456 | return -EINVAL; | |
5dae460c | 457 | } |
0b81d077 | 458 | |
a992b20c EB |
459 | get_random_bytes(nonce, FSCRYPT_FILE_NONCE_SIZE); |
460 | ctxsize = fscrypt_new_context(&ctx, policy, nonce); | |
5dae460c EB |
461 | |
462 | return inode->i_sb->s_cop->set_context(inode, &ctx, ctxsize, NULL); | |
0b81d077 JK |
463 | } |
464 | ||
db717d8e | 465 | int fscrypt_ioctl_set_policy(struct file *filp, const void __user *arg) |
0b81d077 | 466 | { |
5dae460c EB |
467 | union fscrypt_policy policy; |
468 | union fscrypt_policy existing_policy; | |
ba63f23d | 469 | struct inode *inode = file_inode(filp); |
5dae460c EB |
470 | u8 version; |
471 | int size; | |
ba63f23d EB |
472 | int ret; |
473 | ||
5dae460c | 474 | if (get_user(policy.version, (const u8 __user *)arg)) |
db717d8e EB |
475 | return -EFAULT; |
476 | ||
5dae460c EB |
477 | size = fscrypt_policy_size(&policy); |
478 | if (size <= 0) | |
479 | return -EINVAL; | |
480 | ||
481 | /* | |
482 | * We should just copy the remaining 'size - 1' bytes here, but a | |
483 | * bizarre bug in gcc 7 and earlier (fixed by gcc r255731) causes gcc to | |
484 | * think that size can be 0 here (despite the check above!) *and* that | |
485 | * it's a compile-time constant. Thus it would think copy_from_user() | |
486 | * is passed compile-time constant ULONG_MAX, causing the compile-time | |
487 | * buffer overflow check to fail, breaking the build. This only occurred | |
488 | * when building an i386 kernel with -Os and branch profiling enabled. | |
489 | * | |
490 | * Work around it by just copying the first byte again... | |
491 | */ | |
492 | version = policy.version; | |
493 | if (copy_from_user(&policy, arg, size)) | |
494 | return -EFAULT; | |
495 | policy.version = version; | |
496 | ||
21cb47be | 497 | if (!inode_owner_or_capable(&init_user_ns, inode)) |
163ae1c6 EB |
498 | return -EACCES; |
499 | ||
ba63f23d EB |
500 | ret = mnt_want_write_file(filp); |
501 | if (ret) | |
502 | return ret; | |
503 | ||
8906a822 EB |
504 | inode_lock(inode); |
505 | ||
5dae460c | 506 | ret = fscrypt_get_policy(inode, &existing_policy); |
efee590e | 507 | if (ret == -ENODATA) { |
002ced4b | 508 | if (!S_ISDIR(inode->i_mode)) |
dffd0cfa | 509 | ret = -ENOTDIR; |
5858bdad HF |
510 | else if (IS_DEADDIR(inode)) |
511 | ret = -ENOENT; | |
ba63f23d EB |
512 | else if (!inode->i_sb->s_cop->empty_dir(inode)) |
513 | ret = -ENOTEMPTY; | |
514 | else | |
5dae460c EB |
515 | ret = set_encryption_policy(inode, &policy); |
516 | } else if (ret == -EINVAL || | |
517 | (ret == 0 && !fscrypt_policies_equal(&policy, | |
518 | &existing_policy))) { | |
efee590e | 519 | /* The file already uses a different encryption policy. */ |
8488cd96 | 520 | ret = -EEXIST; |
0b81d077 JK |
521 | } |
522 | ||
8906a822 EB |
523 | inode_unlock(inode); |
524 | ||
ba63f23d EB |
525 | mnt_drop_write_file(filp); |
526 | return ret; | |
0b81d077 | 527 | } |
db717d8e | 528 | EXPORT_SYMBOL(fscrypt_ioctl_set_policy); |
0b81d077 | 529 | |
5dae460c | 530 | /* Original ioctl version; can only get the original policy version */ |
db717d8e | 531 | int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg) |
0b81d077 | 532 | { |
5dae460c EB |
533 | union fscrypt_policy policy; |
534 | int err; | |
0b81d077 | 535 | |
5dae460c EB |
536 | err = fscrypt_get_policy(file_inode(filp), &policy); |
537 | if (err) | |
538 | return err; | |
0b81d077 | 539 | |
5dae460c | 540 | if (policy.version != FSCRYPT_POLICY_V1) |
0b81d077 JK |
541 | return -EINVAL; |
542 | ||
5dae460c | 543 | if (copy_to_user(arg, &policy, sizeof(policy.v1))) |
db717d8e | 544 | return -EFAULT; |
0b81d077 JK |
545 | return 0; |
546 | } | |
db717d8e | 547 | EXPORT_SYMBOL(fscrypt_ioctl_get_policy); |
0b81d077 | 548 | |
5dae460c EB |
549 | /* Extended ioctl version; can get policies of any version */ |
550 | int fscrypt_ioctl_get_policy_ex(struct file *filp, void __user *uarg) | |
551 | { | |
552 | struct fscrypt_get_policy_ex_arg arg; | |
553 | union fscrypt_policy *policy = (union fscrypt_policy *)&arg.policy; | |
554 | size_t policy_size; | |
555 | int err; | |
556 | ||
557 | /* arg is policy_size, then policy */ | |
558 | BUILD_BUG_ON(offsetof(typeof(arg), policy_size) != 0); | |
559 | BUILD_BUG_ON(offsetofend(typeof(arg), policy_size) != | |
560 | offsetof(typeof(arg), policy)); | |
561 | BUILD_BUG_ON(sizeof(arg.policy) != sizeof(*policy)); | |
562 | ||
563 | err = fscrypt_get_policy(file_inode(filp), policy); | |
564 | if (err) | |
565 | return err; | |
566 | policy_size = fscrypt_policy_size(policy); | |
567 | ||
568 | if (copy_from_user(&arg, uarg, sizeof(arg.policy_size))) | |
569 | return -EFAULT; | |
570 | ||
571 | if (policy_size > arg.policy_size) | |
572 | return -EOVERFLOW; | |
573 | arg.policy_size = policy_size; | |
574 | ||
575 | if (copy_to_user(uarg, &arg, sizeof(arg.policy_size) + policy_size)) | |
576 | return -EFAULT; | |
577 | return 0; | |
578 | } | |
579 | EXPORT_SYMBOL_GPL(fscrypt_ioctl_get_policy_ex); | |
580 | ||
e98ad464 EB |
581 | /* FS_IOC_GET_ENCRYPTION_NONCE: retrieve file's encryption nonce for testing */ |
582 | int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg) | |
583 | { | |
584 | struct inode *inode = file_inode(filp); | |
585 | union fscrypt_context ctx; | |
586 | int ret; | |
587 | ||
588 | ret = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx)); | |
589 | if (ret < 0) | |
590 | return ret; | |
591 | if (!fscrypt_context_is_valid(&ctx, ret)) | |
592 | return -EINVAL; | |
593 | if (copy_to_user(arg, fscrypt_context_nonce(&ctx), | |
1d6217a4 | 594 | FSCRYPT_FILE_NONCE_SIZE)) |
e98ad464 EB |
595 | return -EFAULT; |
596 | return 0; | |
597 | } | |
598 | EXPORT_SYMBOL_GPL(fscrypt_ioctl_get_nonce); | |
599 | ||
272f98f6 EB |
600 | /** |
601 | * fscrypt_has_permitted_context() - is a file's encryption policy permitted | |
602 | * within its directory? | |
603 | * | |
604 | * @parent: inode for parent directory | |
605 | * @child: inode for file being looked up, opened, or linked into @parent | |
606 | * | |
607 | * Filesystems must call this before permitting access to an inode in a | |
608 | * situation where the parent directory is encrypted (either before allowing | |
609 | * ->lookup() to succeed, or for a regular file before allowing it to be opened) | |
610 | * and before any operation that involves linking an inode into an encrypted | |
611 | * directory, including link, rename, and cross rename. It enforces the | |
612 | * constraint that within a given encrypted directory tree, all files use the | |
613 | * same encryption policy. The pre-access check is needed to detect potentially | |
614 | * malicious offline violations of this constraint, while the link and rename | |
615 | * checks are needed to prevent online violations of this constraint. | |
616 | * | |
f5e55e77 | 617 | * Return: 1 if permitted, 0 if forbidden. |
272f98f6 | 618 | */ |
0b81d077 JK |
619 | int fscrypt_has_permitted_context(struct inode *parent, struct inode *child) |
620 | { | |
5dae460c | 621 | union fscrypt_policy parent_policy, child_policy; |
a14d0b67 | 622 | int err, err1, err2; |
0b81d077 | 623 | |
42d97eb0 EB |
624 | /* No restrictions on file types which are never encrypted */ |
625 | if (!S_ISREG(child->i_mode) && !S_ISDIR(child->i_mode) && | |
626 | !S_ISLNK(child->i_mode)) | |
627 | return 1; | |
628 | ||
272f98f6 | 629 | /* No restrictions if the parent directory is unencrypted */ |
e0428a26 | 630 | if (!IS_ENCRYPTED(parent)) |
0b81d077 | 631 | return 1; |
272f98f6 EB |
632 | |
633 | /* Encrypted directories must not contain unencrypted files */ | |
e0428a26 | 634 | if (!IS_ENCRYPTED(child)) |
0b81d077 | 635 | return 0; |
272f98f6 EB |
636 | |
637 | /* | |
638 | * Both parent and child are encrypted, so verify they use the same | |
639 | * encryption policy. Compare the fscrypt_info structs if the keys are | |
640 | * available, otherwise retrieve and compare the fscrypt_contexts. | |
641 | * | |
642 | * Note that the fscrypt_context retrieval will be required frequently | |
643 | * when accessing an encrypted directory tree without the key. | |
644 | * Performance-wise this is not a big deal because we already don't | |
645 | * really optimize for file access without the key (to the extent that | |
646 | * such access is even possible), given that any attempted access | |
647 | * already causes a fscrypt_context retrieval and keyring search. | |
648 | * | |
649 | * In any case, if an unexpected error occurs, fall back to "forbidden". | |
650 | */ | |
651 | ||
a14d0b67 | 652 | err = fscrypt_get_encryption_info(parent, true); |
5dae460c | 653 | if (err) |
0b81d077 | 654 | return 0; |
a14d0b67 | 655 | err = fscrypt_get_encryption_info(child, true); |
5dae460c | 656 | if (err) |
0b81d077 | 657 | return 0; |
272f98f6 | 658 | |
a14d0b67 EB |
659 | err1 = fscrypt_get_policy(parent, &parent_policy); |
660 | err2 = fscrypt_get_policy(child, &child_policy); | |
272f98f6 | 661 | |
a14d0b67 EB |
662 | /* |
663 | * Allow the case where the parent and child both have an unrecognized | |
664 | * encryption policy, so that files with an unrecognized encryption | |
665 | * policy can be deleted. | |
666 | */ | |
667 | if (err1 == -EINVAL && err2 == -EINVAL) | |
668 | return 1; | |
669 | ||
670 | if (err1 || err2) | |
0b81d077 JK |
671 | return 0; |
672 | ||
5dae460c | 673 | return fscrypt_policies_equal(&parent_policy, &child_policy); |
0b81d077 JK |
674 | } |
675 | EXPORT_SYMBOL(fscrypt_has_permitted_context); | |
676 | ||
ac4acb1f EB |
677 | /* |
678 | * Return the encryption policy that new files in the directory will inherit, or | |
679 | * NULL if none, or an ERR_PTR() on error. If the directory is encrypted, also | |
680 | * ensure that its key is set up, so that the new filename can be encrypted. | |
681 | */ | |
682 | const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir) | |
683 | { | |
684 | int err; | |
685 | ||
686 | if (IS_ENCRYPTED(dir)) { | |
687 | err = fscrypt_require_key(dir); | |
688 | if (err) | |
689 | return ERR_PTR(err); | |
690 | return &dir->i_crypt_info->ci_policy; | |
691 | } | |
692 | ||
693 | return fscrypt_get_dummy_policy(dir->i_sb); | |
694 | } | |
695 | ||
a992b20c EB |
696 | /** |
697 | * fscrypt_set_context() - Set the fscrypt context of a new inode | |
698 | * @inode: a new inode | |
699 | * @fs_data: private data given by FS and passed to ->set_context() | |
700 | * | |
701 | * This should be called after fscrypt_prepare_new_inode(), generally during a | |
702 | * filesystem transaction. Everything here must be %GFP_NOFS-safe. | |
703 | * | |
704 | * Return: 0 on success, -errno on failure | |
705 | */ | |
706 | int fscrypt_set_context(struct inode *inode, void *fs_data) | |
707 | { | |
708 | struct fscrypt_info *ci = inode->i_crypt_info; | |
709 | union fscrypt_context ctx; | |
710 | int ctxsize; | |
711 | ||
712 | /* fscrypt_prepare_new_inode() should have set up the key already. */ | |
713 | if (WARN_ON_ONCE(!ci)) | |
714 | return -ENOKEY; | |
715 | ||
716 | BUILD_BUG_ON(sizeof(ctx) != FSCRYPT_SET_CONTEXT_MAX_SIZE); | |
717 | ctxsize = fscrypt_new_context(&ctx, &ci->ci_policy, ci->ci_nonce); | |
718 | ||
719 | /* | |
720 | * This may be the first time the inode number is available, so do any | |
721 | * delayed key setup that requires the inode number. | |
722 | */ | |
723 | if (ci->ci_policy.version == FSCRYPT_POLICY_V2 && | |
724 | (ci->ci_policy.v2.flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) { | |
725 | const struct fscrypt_master_key *mk = | |
726 | ci->ci_master_key->payload.data[0]; | |
727 | ||
728 | fscrypt_hash_inode_number(ci, mk); | |
729 | } | |
730 | ||
731 | return inode->i_sb->s_cop->set_context(inode, &ctx, ctxsize, fs_data); | |
732 | } | |
733 | EXPORT_SYMBOL_GPL(fscrypt_set_context); | |
734 | ||
ed318a6c | 735 | /** |
218d921b EB |
736 | * fscrypt_parse_test_dummy_encryption() - parse the test_dummy_encryption mount option |
737 | * @param: the mount option | |
738 | * @dummy_policy: (input/output) the place to write the dummy policy that will | |
739 | * result from parsing the option. Zero-initialize this. If a policy is | |
740 | * already set here (due to test_dummy_encryption being given multiple | |
741 | * times), then this function will verify that the policies are the same. | |
ed318a6c | 742 | * |
218d921b EB |
743 | * Return: 0 on success; -EINVAL if the argument is invalid; -EEXIST if the |
744 | * argument conflicts with one already specified; or -ENOMEM. | |
ed318a6c | 745 | */ |
218d921b EB |
746 | int fscrypt_parse_test_dummy_encryption(const struct fs_parameter *param, |
747 | struct fscrypt_dummy_policy *dummy_policy) | |
ed318a6c | 748 | { |
218d921b EB |
749 | const char *arg = "v2"; |
750 | union fscrypt_policy *policy; | |
ed318a6c EB |
751 | int err; |
752 | ||
218d921b EB |
753 | if (param->type == fs_value_is_string && *param->string) |
754 | arg = param->string; | |
ed318a6c | 755 | |
ac4acb1f | 756 | policy = kzalloc(sizeof(*policy), GFP_KERNEL); |
218d921b EB |
757 | if (!policy) |
758 | return -ENOMEM; | |
ed318a6c | 759 | |
218d921b EB |
760 | if (!strcmp(arg, "v1")) { |
761 | policy->version = FSCRYPT_POLICY_V1; | |
ac4acb1f EB |
762 | policy->v1.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS; |
763 | policy->v1.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS; | |
218d921b | 764 | memset(policy->v1.master_key_descriptor, 0x42, |
ed318a6c | 765 | FSCRYPT_KEY_DESCRIPTOR_SIZE); |
218d921b EB |
766 | } else if (!strcmp(arg, "v2")) { |
767 | policy->version = FSCRYPT_POLICY_V2; | |
ac4acb1f EB |
768 | policy->v2.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS; |
769 | policy->v2.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS; | |
218d921b EB |
770 | err = fscrypt_get_test_dummy_key_identifier( |
771 | policy->v2.master_key_identifier); | |
772 | if (err) | |
773 | goto out; | |
774 | } else { | |
ed318a6c EB |
775 | err = -EINVAL; |
776 | goto out; | |
777 | } | |
ac4acb1f EB |
778 | |
779 | if (dummy_policy->policy) { | |
780 | if (fscrypt_policies_equal(policy, dummy_policy->policy)) | |
781 | err = 0; | |
782 | else | |
783 | err = -EEXIST; | |
784 | goto out; | |
785 | } | |
786 | dummy_policy->policy = policy; | |
787 | policy = NULL; | |
ed318a6c EB |
788 | err = 0; |
789 | out: | |
ac4acb1f | 790 | kfree(policy); |
ed318a6c EB |
791 | return err; |
792 | } | |
218d921b EB |
793 | EXPORT_SYMBOL_GPL(fscrypt_parse_test_dummy_encryption); |
794 | ||
795 | /** | |
796 | * fscrypt_dummy_policies_equal() - check whether two dummy policies are equal | |
797 | * @p1: the first test dummy policy (may be unset) | |
798 | * @p2: the second test dummy policy (may be unset) | |
799 | * | |
800 | * Return: %true if the dummy policies are both set and equal, or both unset. | |
801 | */ | |
802 | bool fscrypt_dummy_policies_equal(const struct fscrypt_dummy_policy *p1, | |
803 | const struct fscrypt_dummy_policy *p2) | |
804 | { | |
805 | if (!p1->policy && !p2->policy) | |
806 | return true; | |
807 | if (!p1->policy || !p2->policy) | |
808 | return false; | |
809 | return fscrypt_policies_equal(p1->policy, p2->policy); | |
810 | } | |
811 | EXPORT_SYMBOL_GPL(fscrypt_dummy_policies_equal); | |
812 | ||
813 | /* Deprecated, do not use */ | |
814 | int fscrypt_set_test_dummy_encryption(struct super_block *sb, const char *arg, | |
815 | struct fscrypt_dummy_policy *dummy_policy) | |
816 | { | |
817 | struct fs_parameter param = { | |
818 | .type = fs_value_is_string, | |
819 | .string = arg ? (char *)arg : "", | |
820 | }; | |
821 | return fscrypt_parse_test_dummy_encryption(¶m, dummy_policy) ?: | |
822 | fscrypt_add_test_dummy_key(sb, dummy_policy); | |
823 | } | |
ed318a6c EB |
824 | EXPORT_SYMBOL_GPL(fscrypt_set_test_dummy_encryption); |
825 | ||
826 | /** | |
827 | * fscrypt_show_test_dummy_encryption() - show '-o test_dummy_encryption' | |
828 | * @seq: the seq_file to print the option to | |
829 | * @sep: the separator character to use | |
830 | * @sb: the filesystem whose options are being shown | |
831 | * | |
832 | * Show the test_dummy_encryption mount option, if it was specified. | |
833 | * This is mainly used for /proc/mounts. | |
834 | */ | |
835 | void fscrypt_show_test_dummy_encryption(struct seq_file *seq, char sep, | |
836 | struct super_block *sb) | |
837 | { | |
ac4acb1f EB |
838 | const union fscrypt_policy *policy = fscrypt_get_dummy_policy(sb); |
839 | int vers; | |
ed318a6c | 840 | |
ac4acb1f | 841 | if (!policy) |
ed318a6c | 842 | return; |
ac4acb1f EB |
843 | |
844 | vers = policy->version; | |
845 | if (vers == FSCRYPT_POLICY_V1) /* Handle numbering quirk */ | |
846 | vers = 1; | |
847 | ||
848 | seq_printf(seq, "%ctest_dummy_encryption=v%d", sep, vers); | |
ed318a6c EB |
849 | } |
850 | EXPORT_SYMBOL_GPL(fscrypt_show_test_dummy_encryption); |