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: | |
41b2ad80 | 51 | WARN_ON_ONCE(1); |
bfb9700b EB |
52 | return -EINVAL; |
53 | } | |
54 | } | |
55 | ||
60e463f0 | 56 | const union fscrypt_policy *fscrypt_get_dummy_policy(struct super_block *sb) |
ac4acb1f EB |
57 | { |
58 | if (!sb->s_cop->get_dummy_policy) | |
59 | return NULL; | |
60 | return sb->s_cop->get_dummy_policy(sb); | |
61 | } | |
62 | ||
aa997990 EB |
63 | /* |
64 | * Return %true if the given combination of encryption modes is supported for v1 | |
65 | * (and later) encryption policies. | |
66 | * | |
67 | * Do *not* add anything new here, since v1 encryption policies are deprecated. | |
68 | * New combinations of modes should go in fscrypt_valid_enc_modes_v2() only. | |
69 | */ | |
6b2a51ff | 70 | static bool fscrypt_valid_enc_modes_v1(u32 contents_mode, u32 filenames_mode) |
ef5b18b0 EB |
71 | { |
72 | if (contents_mode == FSCRYPT_MODE_AES_256_XTS && | |
73 | filenames_mode == FSCRYPT_MODE_AES_256_CTS) | |
74 | return true; | |
75 | ||
76 | if (contents_mode == FSCRYPT_MODE_AES_128_CBC && | |
77 | filenames_mode == FSCRYPT_MODE_AES_128_CTS) | |
78 | return true; | |
79 | ||
80 | if (contents_mode == FSCRYPT_MODE_ADIANTUM && | |
81 | filenames_mode == FSCRYPT_MODE_ADIANTUM) | |
82 | return true; | |
83 | ||
84 | return false; | |
85 | } | |
86 | ||
6b2a51ff NH |
87 | static bool fscrypt_valid_enc_modes_v2(u32 contents_mode, u32 filenames_mode) |
88 | { | |
89 | if (contents_mode == FSCRYPT_MODE_AES_256_XTS && | |
90 | filenames_mode == FSCRYPT_MODE_AES_256_HCTR2) | |
91 | return true; | |
e0cefada TZ |
92 | |
93 | if (contents_mode == FSCRYPT_MODE_SM4_XTS && | |
94 | filenames_mode == FSCRYPT_MODE_SM4_CTS) | |
95 | return true; | |
96 | ||
6b2a51ff NH |
97 | return fscrypt_valid_enc_modes_v1(contents_mode, filenames_mode); |
98 | } | |
99 | ||
85af90e5 EB |
100 | static bool supported_direct_key_modes(const struct inode *inode, |
101 | u32 contents_mode, u32 filenames_mode) | |
102 | { | |
103 | const struct fscrypt_mode *mode; | |
104 | ||
105 | if (contents_mode != filenames_mode) { | |
106 | fscrypt_warn(inode, | |
107 | "Direct key flag not allowed with different contents and filenames modes"); | |
108 | return false; | |
109 | } | |
110 | mode = &fscrypt_modes[contents_mode]; | |
111 | ||
112 | if (mode->ivsize < offsetofend(union fscrypt_iv, nonce)) { | |
113 | fscrypt_warn(inode, "Direct key flag not allowed with %s", | |
114 | mode->friendly_name); | |
115 | return false; | |
116 | } | |
117 | return true; | |
118 | } | |
119 | ||
e3b1078b EB |
120 | static bool supported_iv_ino_lblk_policy(const struct fscrypt_policy_v2 *policy, |
121 | const struct inode *inode, | |
122 | const char *type, | |
123 | int max_ino_bits, int max_lblk_bits) | |
b103fb76 EB |
124 | { |
125 | struct super_block *sb = inode->i_sb; | |
126 | int ino_bits = 64, lblk_bits = 64; | |
127 | ||
f000223c EB |
128 | /* |
129 | * IV_INO_LBLK_* exist only because of hardware limitations, and | |
130 | * currently the only known use case for them involves AES-256-XTS. | |
131 | * That's also all we test currently. For these reasons, for now only | |
132 | * allow AES-256-XTS here. This can be relaxed later if a use case for | |
133 | * IV_INO_LBLK_* with other encryption modes arises. | |
134 | */ | |
135 | if (policy->contents_encryption_mode != FSCRYPT_MODE_AES_256_XTS) { | |
136 | fscrypt_warn(inode, | |
137 | "Can't use %s policy with contents mode other than AES-256-XTS", | |
138 | type); | |
139 | return false; | |
140 | } | |
141 | ||
b103fb76 EB |
142 | /* |
143 | * It's unsafe to include inode numbers in the IVs if the filesystem can | |
144 | * potentially renumber inodes, e.g. via filesystem shrinking. | |
145 | */ | |
146 | if (!sb->s_cop->has_stable_inodes || | |
147 | !sb->s_cop->has_stable_inodes(sb)) { | |
148 | fscrypt_warn(inode, | |
e3b1078b EB |
149 | "Can't use %s policy on filesystem '%s' because it doesn't have stable inode numbers", |
150 | type, sb->s_id); | |
b103fb76 EB |
151 | return false; |
152 | } | |
153 | if (sb->s_cop->get_ino_and_lblk_bits) | |
154 | sb->s_cop->get_ino_and_lblk_bits(sb, &ino_bits, &lblk_bits); | |
e3b1078b EB |
155 | if (ino_bits > max_ino_bits) { |
156 | fscrypt_warn(inode, | |
157 | "Can't use %s policy on filesystem '%s' because its inode numbers are too long", | |
158 | type, sb->s_id); | |
159 | return false; | |
160 | } | |
161 | if (lblk_bits > max_lblk_bits) { | |
b103fb76 | 162 | fscrypt_warn(inode, |
e3b1078b EB |
163 | "Can't use %s policy on filesystem '%s' because its block numbers are too long", |
164 | type, sb->s_id); | |
b103fb76 EB |
165 | return false; |
166 | } | |
167 | return true; | |
168 | } | |
169 | ||
393a24a7 EB |
170 | static bool fscrypt_supported_v1_policy(const struct fscrypt_policy_v1 *policy, |
171 | const struct inode *inode) | |
172 | { | |
6b2a51ff | 173 | if (!fscrypt_valid_enc_modes_v1(policy->contents_encryption_mode, |
393a24a7 EB |
174 | policy->filenames_encryption_mode)) { |
175 | fscrypt_warn(inode, | |
176 | "Unsupported encryption modes (contents %d, filenames %d)", | |
177 | policy->contents_encryption_mode, | |
178 | policy->filenames_encryption_mode); | |
179 | return false; | |
180 | } | |
181 | ||
182 | if (policy->flags & ~(FSCRYPT_POLICY_FLAGS_PAD_MASK | | |
183 | FSCRYPT_POLICY_FLAG_DIRECT_KEY)) { | |
184 | fscrypt_warn(inode, "Unsupported encryption flags (0x%02x)", | |
185 | policy->flags); | |
186 | return false; | |
187 | } | |
188 | ||
85af90e5 EB |
189 | if ((policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) && |
190 | !supported_direct_key_modes(inode, policy->contents_encryption_mode, | |
191 | policy->filenames_encryption_mode)) | |
192 | return false; | |
193 | ||
6e1918cf DR |
194 | if (IS_CASEFOLDED(inode)) { |
195 | /* With v1, there's no way to derive dirhash keys. */ | |
196 | fscrypt_warn(inode, | |
197 | "v1 policies can't be used on casefolded directories"); | |
198 | return false; | |
199 | } | |
200 | ||
393a24a7 EB |
201 | return true; |
202 | } | |
203 | ||
204 | static bool fscrypt_supported_v2_policy(const struct fscrypt_policy_v2 *policy, | |
205 | const struct inode *inode) | |
206 | { | |
e3b1078b EB |
207 | int count = 0; |
208 | ||
6b2a51ff | 209 | if (!fscrypt_valid_enc_modes_v2(policy->contents_encryption_mode, |
393a24a7 EB |
210 | policy->filenames_encryption_mode)) { |
211 | fscrypt_warn(inode, | |
212 | "Unsupported encryption modes (contents %d, filenames %d)", | |
213 | policy->contents_encryption_mode, | |
214 | policy->filenames_encryption_mode); | |
215 | return false; | |
216 | } | |
217 | ||
3ceb6543 EB |
218 | if (policy->flags & ~(FSCRYPT_POLICY_FLAGS_PAD_MASK | |
219 | FSCRYPT_POLICY_FLAG_DIRECT_KEY | | |
220 | FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64 | | |
221 | FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) { | |
393a24a7 EB |
222 | fscrypt_warn(inode, "Unsupported encryption flags (0x%02x)", |
223 | policy->flags); | |
224 | return false; | |
225 | } | |
226 | ||
e3b1078b EB |
227 | count += !!(policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY); |
228 | count += !!(policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64); | |
229 | count += !!(policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32); | |
230 | if (count > 1) { | |
231 | fscrypt_warn(inode, "Mutually exclusive encryption flags (0x%02x)", | |
232 | policy->flags); | |
233 | return false; | |
234 | } | |
235 | ||
85af90e5 EB |
236 | if ((policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) && |
237 | !supported_direct_key_modes(inode, policy->contents_encryption_mode, | |
238 | policy->filenames_encryption_mode)) | |
239 | return false; | |
240 | ||
393a24a7 | 241 | if ((policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) && |
e3b1078b EB |
242 | !supported_iv_ino_lblk_policy(policy, inode, "IV_INO_LBLK_64", |
243 | 32, 32)) | |
244 | return false; | |
245 | ||
5e895bd4 EB |
246 | /* |
247 | * IV_INO_LBLK_32 hashes the inode number, so in principle it can | |
248 | * support any ino_bits. However, currently the inode number is gotten | |
249 | * from inode::i_ino which is 'unsigned long'. So for now the | |
250 | * implementation limit is 32 bits. | |
251 | */ | |
e3b1078b | 252 | if ((policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) && |
e3b1078b | 253 | !supported_iv_ino_lblk_policy(policy, inode, "IV_INO_LBLK_32", |
5e895bd4 | 254 | 32, 32)) |
393a24a7 EB |
255 | return false; |
256 | ||
257 | if (memchr_inv(policy->__reserved, 0, sizeof(policy->__reserved))) { | |
258 | fscrypt_warn(inode, "Reserved bits set in encryption policy"); | |
259 | return false; | |
260 | } | |
261 | ||
262 | return true; | |
263 | } | |
264 | ||
5dae460c | 265 | /** |
d2fe9754 EB |
266 | * fscrypt_supported_policy() - check whether an encryption policy is supported |
267 | * @policy_u: the encryption policy | |
268 | * @inode: the inode on which the policy will be used | |
5dae460c EB |
269 | * |
270 | * Given an encryption policy, check whether all its encryption modes and other | |
393a24a7 EB |
271 | * settings are supported by this kernel on the given inode. (But we don't |
272 | * currently don't check for crypto API support here, so attempting to use an | |
273 | * algorithm not configured into the crypto API will still fail later.) | |
5dae460c EB |
274 | * |
275 | * Return: %true if supported, else %false | |
276 | */ | |
277 | bool fscrypt_supported_policy(const union fscrypt_policy *policy_u, | |
278 | const struct inode *inode) | |
0b81d077 | 279 | { |
5dae460c | 280 | switch (policy_u->version) { |
393a24a7 EB |
281 | case FSCRYPT_POLICY_V1: |
282 | return fscrypt_supported_v1_policy(&policy_u->v1, inode); | |
283 | case FSCRYPT_POLICY_V2: | |
284 | return fscrypt_supported_v2_policy(&policy_u->v2, inode); | |
5dae460c EB |
285 | } |
286 | return false; | |
287 | } | |
288 | ||
289 | /** | |
a992b20c | 290 | * fscrypt_new_context() - create a new fscrypt_context |
d2fe9754 EB |
291 | * @ctx_u: output context |
292 | * @policy_u: input policy | |
a992b20c | 293 | * @nonce: nonce to use |
5dae460c EB |
294 | * |
295 | * Create an fscrypt_context for an inode that is being assigned the given | |
a992b20c | 296 | * encryption policy. @nonce must be a new random nonce. |
5dae460c EB |
297 | * |
298 | * Return: the size of the new context in bytes. | |
299 | */ | |
a992b20c EB |
300 | static int fscrypt_new_context(union fscrypt_context *ctx_u, |
301 | const union fscrypt_policy *policy_u, | |
302 | const u8 nonce[FSCRYPT_FILE_NONCE_SIZE]) | |
5dae460c EB |
303 | { |
304 | memset(ctx_u, 0, sizeof(*ctx_u)); | |
305 | ||
306 | switch (policy_u->version) { | |
307 | case FSCRYPT_POLICY_V1: { | |
308 | const struct fscrypt_policy_v1 *policy = &policy_u->v1; | |
309 | struct fscrypt_context_v1 *ctx = &ctx_u->v1; | |
310 | ||
311 | ctx->version = FSCRYPT_CONTEXT_V1; | |
312 | ctx->contents_encryption_mode = | |
313 | policy->contents_encryption_mode; | |
314 | ctx->filenames_encryption_mode = | |
315 | policy->filenames_encryption_mode; | |
316 | ctx->flags = policy->flags; | |
317 | memcpy(ctx->master_key_descriptor, | |
318 | policy->master_key_descriptor, | |
319 | sizeof(ctx->master_key_descriptor)); | |
a992b20c | 320 | memcpy(ctx->nonce, nonce, FSCRYPT_FILE_NONCE_SIZE); |
5dae460c EB |
321 | return sizeof(*ctx); |
322 | } | |
323 | case FSCRYPT_POLICY_V2: { | |
324 | const struct fscrypt_policy_v2 *policy = &policy_u->v2; | |
325 | struct fscrypt_context_v2 *ctx = &ctx_u->v2; | |
326 | ||
327 | ctx->version = FSCRYPT_CONTEXT_V2; | |
328 | ctx->contents_encryption_mode = | |
329 | policy->contents_encryption_mode; | |
330 | ctx->filenames_encryption_mode = | |
331 | policy->filenames_encryption_mode; | |
332 | ctx->flags = policy->flags; | |
333 | memcpy(ctx->master_key_identifier, | |
334 | policy->master_key_identifier, | |
335 | sizeof(ctx->master_key_identifier)); | |
a992b20c | 336 | memcpy(ctx->nonce, nonce, FSCRYPT_FILE_NONCE_SIZE); |
5dae460c EB |
337 | return sizeof(*ctx); |
338 | } | |
339 | } | |
340 | BUG(); | |
341 | } | |
0b81d077 | 342 | |
5dae460c | 343 | /** |
d2fe9754 EB |
344 | * fscrypt_policy_from_context() - convert an fscrypt_context to |
345 | * an fscrypt_policy | |
346 | * @policy_u: output policy | |
347 | * @ctx_u: input context | |
348 | * @ctx_size: size of input context in bytes | |
5dae460c EB |
349 | * |
350 | * Given an fscrypt_context, build the corresponding fscrypt_policy. | |
351 | * | |
352 | * Return: 0 on success, or -EINVAL if the fscrypt_context has an unrecognized | |
353 | * version number or size. | |
354 | * | |
355 | * This does *not* validate the settings within the policy itself, e.g. the | |
356 | * modes, flags, and reserved bits. Use fscrypt_supported_policy() for that. | |
357 | */ | |
358 | int fscrypt_policy_from_context(union fscrypt_policy *policy_u, | |
359 | const union fscrypt_context *ctx_u, | |
360 | int ctx_size) | |
361 | { | |
362 | memset(policy_u, 0, sizeof(*policy_u)); | |
0b81d077 | 363 | |
e98ad464 | 364 | if (!fscrypt_context_is_valid(ctx_u, ctx_size)) |
0b81d077 | 365 | return -EINVAL; |
0b81d077 | 366 | |
5dae460c EB |
367 | switch (ctx_u->version) { |
368 | case FSCRYPT_CONTEXT_V1: { | |
369 | const struct fscrypt_context_v1 *ctx = &ctx_u->v1; | |
370 | struct fscrypt_policy_v1 *policy = &policy_u->v1; | |
371 | ||
372 | policy->version = FSCRYPT_POLICY_V1; | |
373 | policy->contents_encryption_mode = | |
374 | ctx->contents_encryption_mode; | |
375 | policy->filenames_encryption_mode = | |
376 | ctx->filenames_encryption_mode; | |
377 | policy->flags = ctx->flags; | |
378 | memcpy(policy->master_key_descriptor, | |
379 | ctx->master_key_descriptor, | |
380 | sizeof(policy->master_key_descriptor)); | |
381 | return 0; | |
382 | } | |
383 | case FSCRYPT_CONTEXT_V2: { | |
384 | const struct fscrypt_context_v2 *ctx = &ctx_u->v2; | |
385 | struct fscrypt_policy_v2 *policy = &policy_u->v2; | |
386 | ||
387 | policy->version = FSCRYPT_POLICY_V2; | |
388 | policy->contents_encryption_mode = | |
389 | ctx->contents_encryption_mode; | |
390 | policy->filenames_encryption_mode = | |
391 | ctx->filenames_encryption_mode; | |
392 | policy->flags = ctx->flags; | |
393 | memcpy(policy->__reserved, ctx->__reserved, | |
394 | sizeof(policy->__reserved)); | |
395 | memcpy(policy->master_key_identifier, | |
396 | ctx->master_key_identifier, | |
397 | sizeof(policy->master_key_identifier)); | |
398 | return 0; | |
399 | } | |
400 | } | |
401 | /* unreachable */ | |
402 | return -EINVAL; | |
403 | } | |
404 | ||
405 | /* Retrieve an inode's encryption policy */ | |
406 | static int fscrypt_get_policy(struct inode *inode, union fscrypt_policy *policy) | |
407 | { | |
408 | const struct fscrypt_info *ci; | |
409 | union fscrypt_context ctx; | |
410 | int ret; | |
411 | ||
ab673b98 | 412 | ci = fscrypt_get_info(inode); |
5dae460c EB |
413 | if (ci) { |
414 | /* key available, use the cached policy */ | |
415 | *policy = ci->ci_policy; | |
416 | return 0; | |
417 | } | |
418 | ||
419 | if (!IS_ENCRYPTED(inode)) | |
420 | return -ENODATA; | |
421 | ||
422 | ret = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx)); | |
423 | if (ret < 0) | |
424 | return (ret == -ERANGE) ? -EINVAL : ret; | |
425 | ||
426 | return fscrypt_policy_from_context(policy, &ctx, ret); | |
427 | } | |
428 | ||
429 | static int set_encryption_policy(struct inode *inode, | |
430 | const union fscrypt_policy *policy) | |
431 | { | |
a992b20c | 432 | u8 nonce[FSCRYPT_FILE_NONCE_SIZE]; |
5dae460c EB |
433 | union fscrypt_context ctx; |
434 | int ctxsize; | |
5ab7189a | 435 | int err; |
5dae460c EB |
436 | |
437 | if (!fscrypt_supported_policy(policy, inode)) | |
0b81d077 JK |
438 | return -EINVAL; |
439 | ||
5ab7189a EB |
440 | switch (policy->version) { |
441 | case FSCRYPT_POLICY_V1: | |
5dae460c EB |
442 | /* |
443 | * The original encryption policy version provided no way of | |
444 | * verifying that the correct master key was supplied, which was | |
445 | * insecure in scenarios where multiple users have access to the | |
446 | * same encrypted files (even just read-only access). The new | |
447 | * encryption policy version fixes this and also implies use of | |
448 | * an improved key derivation function and allows non-root users | |
449 | * to securely remove keys. So as long as compatibility with | |
450 | * old kernels isn't required, it is recommended to use the new | |
451 | * policy version for all new encrypted directories. | |
452 | */ | |
453 | pr_warn_once("%s (pid %d) is setting deprecated v1 encryption policy; recommend upgrading to v2.\n", | |
454 | current->comm, current->pid); | |
5ab7189a EB |
455 | break; |
456 | case FSCRYPT_POLICY_V2: | |
457 | err = fscrypt_verify_key_added(inode->i_sb, | |
458 | policy->v2.master_key_identifier); | |
459 | if (err) | |
460 | return err; | |
e3b1078b EB |
461 | if (policy->v2.flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) |
462 | 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", | |
463 | current->comm, current->pid); | |
5ab7189a EB |
464 | break; |
465 | default: | |
41b2ad80 | 466 | WARN_ON_ONCE(1); |
5ab7189a | 467 | return -EINVAL; |
5dae460c | 468 | } |
0b81d077 | 469 | |
a992b20c EB |
470 | get_random_bytes(nonce, FSCRYPT_FILE_NONCE_SIZE); |
471 | ctxsize = fscrypt_new_context(&ctx, policy, nonce); | |
5dae460c EB |
472 | |
473 | return inode->i_sb->s_cop->set_context(inode, &ctx, ctxsize, NULL); | |
0b81d077 JK |
474 | } |
475 | ||
db717d8e | 476 | int fscrypt_ioctl_set_policy(struct file *filp, const void __user *arg) |
0b81d077 | 477 | { |
5dae460c EB |
478 | union fscrypt_policy policy; |
479 | union fscrypt_policy existing_policy; | |
ba63f23d | 480 | struct inode *inode = file_inode(filp); |
5dae460c EB |
481 | u8 version; |
482 | int size; | |
ba63f23d EB |
483 | int ret; |
484 | ||
5dae460c | 485 | if (get_user(policy.version, (const u8 __user *)arg)) |
db717d8e EB |
486 | return -EFAULT; |
487 | ||
5dae460c EB |
488 | size = fscrypt_policy_size(&policy); |
489 | if (size <= 0) | |
490 | return -EINVAL; | |
491 | ||
492 | /* | |
493 | * We should just copy the remaining 'size - 1' bytes here, but a | |
494 | * bizarre bug in gcc 7 and earlier (fixed by gcc r255731) causes gcc to | |
495 | * think that size can be 0 here (despite the check above!) *and* that | |
496 | * it's a compile-time constant. Thus it would think copy_from_user() | |
497 | * is passed compile-time constant ULONG_MAX, causing the compile-time | |
498 | * buffer overflow check to fail, breaking the build. This only occurred | |
499 | * when building an i386 kernel with -Os and branch profiling enabled. | |
500 | * | |
501 | * Work around it by just copying the first byte again... | |
502 | */ | |
503 | version = policy.version; | |
504 | if (copy_from_user(&policy, arg, size)) | |
505 | return -EFAULT; | |
506 | policy.version = version; | |
507 | ||
01beba79 | 508 | if (!inode_owner_or_capable(&nop_mnt_idmap, inode)) |
163ae1c6 EB |
509 | return -EACCES; |
510 | ||
ba63f23d EB |
511 | ret = mnt_want_write_file(filp); |
512 | if (ret) | |
513 | return ret; | |
514 | ||
8906a822 EB |
515 | inode_lock(inode); |
516 | ||
5dae460c | 517 | ret = fscrypt_get_policy(inode, &existing_policy); |
efee590e | 518 | if (ret == -ENODATA) { |
002ced4b | 519 | if (!S_ISDIR(inode->i_mode)) |
dffd0cfa | 520 | ret = -ENOTDIR; |
5858bdad HF |
521 | else if (IS_DEADDIR(inode)) |
522 | ret = -ENOENT; | |
ba63f23d EB |
523 | else if (!inode->i_sb->s_cop->empty_dir(inode)) |
524 | ret = -ENOTEMPTY; | |
525 | else | |
5dae460c EB |
526 | ret = set_encryption_policy(inode, &policy); |
527 | } else if (ret == -EINVAL || | |
528 | (ret == 0 && !fscrypt_policies_equal(&policy, | |
529 | &existing_policy))) { | |
efee590e | 530 | /* The file already uses a different encryption policy. */ |
8488cd96 | 531 | ret = -EEXIST; |
0b81d077 JK |
532 | } |
533 | ||
8906a822 EB |
534 | inode_unlock(inode); |
535 | ||
ba63f23d EB |
536 | mnt_drop_write_file(filp); |
537 | return ret; | |
0b81d077 | 538 | } |
db717d8e | 539 | EXPORT_SYMBOL(fscrypt_ioctl_set_policy); |
0b81d077 | 540 | |
5dae460c | 541 | /* Original ioctl version; can only get the original policy version */ |
db717d8e | 542 | int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg) |
0b81d077 | 543 | { |
5dae460c EB |
544 | union fscrypt_policy policy; |
545 | int err; | |
0b81d077 | 546 | |
5dae460c EB |
547 | err = fscrypt_get_policy(file_inode(filp), &policy); |
548 | if (err) | |
549 | return err; | |
0b81d077 | 550 | |
5dae460c | 551 | if (policy.version != FSCRYPT_POLICY_V1) |
0b81d077 JK |
552 | return -EINVAL; |
553 | ||
5dae460c | 554 | if (copy_to_user(arg, &policy, sizeof(policy.v1))) |
db717d8e | 555 | return -EFAULT; |
0b81d077 JK |
556 | return 0; |
557 | } | |
db717d8e | 558 | EXPORT_SYMBOL(fscrypt_ioctl_get_policy); |
0b81d077 | 559 | |
5dae460c EB |
560 | /* Extended ioctl version; can get policies of any version */ |
561 | int fscrypt_ioctl_get_policy_ex(struct file *filp, void __user *uarg) | |
562 | { | |
563 | struct fscrypt_get_policy_ex_arg arg; | |
564 | union fscrypt_policy *policy = (union fscrypt_policy *)&arg.policy; | |
565 | size_t policy_size; | |
566 | int err; | |
567 | ||
568 | /* arg is policy_size, then policy */ | |
569 | BUILD_BUG_ON(offsetof(typeof(arg), policy_size) != 0); | |
570 | BUILD_BUG_ON(offsetofend(typeof(arg), policy_size) != | |
571 | offsetof(typeof(arg), policy)); | |
572 | BUILD_BUG_ON(sizeof(arg.policy) != sizeof(*policy)); | |
573 | ||
574 | err = fscrypt_get_policy(file_inode(filp), policy); | |
575 | if (err) | |
576 | return err; | |
577 | policy_size = fscrypt_policy_size(policy); | |
578 | ||
579 | if (copy_from_user(&arg, uarg, sizeof(arg.policy_size))) | |
580 | return -EFAULT; | |
581 | ||
582 | if (policy_size > arg.policy_size) | |
583 | return -EOVERFLOW; | |
584 | arg.policy_size = policy_size; | |
585 | ||
586 | if (copy_to_user(uarg, &arg, sizeof(arg.policy_size) + policy_size)) | |
587 | return -EFAULT; | |
588 | return 0; | |
589 | } | |
590 | EXPORT_SYMBOL_GPL(fscrypt_ioctl_get_policy_ex); | |
591 | ||
e98ad464 EB |
592 | /* FS_IOC_GET_ENCRYPTION_NONCE: retrieve file's encryption nonce for testing */ |
593 | int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg) | |
594 | { | |
595 | struct inode *inode = file_inode(filp); | |
596 | union fscrypt_context ctx; | |
597 | int ret; | |
598 | ||
599 | ret = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx)); | |
600 | if (ret < 0) | |
601 | return ret; | |
602 | if (!fscrypt_context_is_valid(&ctx, ret)) | |
603 | return -EINVAL; | |
604 | if (copy_to_user(arg, fscrypt_context_nonce(&ctx), | |
1d6217a4 | 605 | FSCRYPT_FILE_NONCE_SIZE)) |
e98ad464 EB |
606 | return -EFAULT; |
607 | return 0; | |
608 | } | |
609 | EXPORT_SYMBOL_GPL(fscrypt_ioctl_get_nonce); | |
610 | ||
272f98f6 EB |
611 | /** |
612 | * fscrypt_has_permitted_context() - is a file's encryption policy permitted | |
613 | * within its directory? | |
614 | * | |
615 | * @parent: inode for parent directory | |
616 | * @child: inode for file being looked up, opened, or linked into @parent | |
617 | * | |
618 | * Filesystems must call this before permitting access to an inode in a | |
619 | * situation where the parent directory is encrypted (either before allowing | |
620 | * ->lookup() to succeed, or for a regular file before allowing it to be opened) | |
621 | * and before any operation that involves linking an inode into an encrypted | |
622 | * directory, including link, rename, and cross rename. It enforces the | |
623 | * constraint that within a given encrypted directory tree, all files use the | |
624 | * same encryption policy. The pre-access check is needed to detect potentially | |
625 | * malicious offline violations of this constraint, while the link and rename | |
626 | * checks are needed to prevent online violations of this constraint. | |
627 | * | |
f5e55e77 | 628 | * Return: 1 if permitted, 0 if forbidden. |
272f98f6 | 629 | */ |
0b81d077 JK |
630 | int fscrypt_has_permitted_context(struct inode *parent, struct inode *child) |
631 | { | |
5dae460c | 632 | union fscrypt_policy parent_policy, child_policy; |
a14d0b67 | 633 | int err, err1, err2; |
0b81d077 | 634 | |
42d97eb0 EB |
635 | /* No restrictions on file types which are never encrypted */ |
636 | if (!S_ISREG(child->i_mode) && !S_ISDIR(child->i_mode) && | |
637 | !S_ISLNK(child->i_mode)) | |
638 | return 1; | |
639 | ||
272f98f6 | 640 | /* No restrictions if the parent directory is unencrypted */ |
e0428a26 | 641 | if (!IS_ENCRYPTED(parent)) |
0b81d077 | 642 | return 1; |
272f98f6 EB |
643 | |
644 | /* Encrypted directories must not contain unencrypted files */ | |
e0428a26 | 645 | if (!IS_ENCRYPTED(child)) |
0b81d077 | 646 | return 0; |
272f98f6 EB |
647 | |
648 | /* | |
649 | * Both parent and child are encrypted, so verify they use the same | |
650 | * encryption policy. Compare the fscrypt_info structs if the keys are | |
651 | * available, otherwise retrieve and compare the fscrypt_contexts. | |
652 | * | |
653 | * Note that the fscrypt_context retrieval will be required frequently | |
654 | * when accessing an encrypted directory tree without the key. | |
655 | * Performance-wise this is not a big deal because we already don't | |
656 | * really optimize for file access without the key (to the extent that | |
657 | * such access is even possible), given that any attempted access | |
658 | * already causes a fscrypt_context retrieval and keyring search. | |
659 | * | |
660 | * In any case, if an unexpected error occurs, fall back to "forbidden". | |
661 | */ | |
662 | ||
a14d0b67 | 663 | err = fscrypt_get_encryption_info(parent, true); |
5dae460c | 664 | if (err) |
0b81d077 | 665 | return 0; |
a14d0b67 | 666 | err = fscrypt_get_encryption_info(child, true); |
5dae460c | 667 | if (err) |
0b81d077 | 668 | return 0; |
272f98f6 | 669 | |
a14d0b67 EB |
670 | err1 = fscrypt_get_policy(parent, &parent_policy); |
671 | err2 = fscrypt_get_policy(child, &child_policy); | |
272f98f6 | 672 | |
a14d0b67 EB |
673 | /* |
674 | * Allow the case where the parent and child both have an unrecognized | |
675 | * encryption policy, so that files with an unrecognized encryption | |
676 | * policy can be deleted. | |
677 | */ | |
678 | if (err1 == -EINVAL && err2 == -EINVAL) | |
679 | return 1; | |
680 | ||
681 | if (err1 || err2) | |
0b81d077 JK |
682 | return 0; |
683 | ||
5dae460c | 684 | return fscrypt_policies_equal(&parent_policy, &child_policy); |
0b81d077 JK |
685 | } |
686 | EXPORT_SYMBOL(fscrypt_has_permitted_context); | |
687 | ||
ac4acb1f EB |
688 | /* |
689 | * Return the encryption policy that new files in the directory will inherit, or | |
690 | * NULL if none, or an ERR_PTR() on error. If the directory is encrypted, also | |
691 | * ensure that its key is set up, so that the new filename can be encrypted. | |
692 | */ | |
693 | const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir) | |
694 | { | |
695 | int err; | |
696 | ||
697 | if (IS_ENCRYPTED(dir)) { | |
698 | err = fscrypt_require_key(dir); | |
699 | if (err) | |
700 | return ERR_PTR(err); | |
701 | return &dir->i_crypt_info->ci_policy; | |
702 | } | |
703 | ||
704 | return fscrypt_get_dummy_policy(dir->i_sb); | |
705 | } | |
706 | ||
637fa738 JL |
707 | /** |
708 | * fscrypt_context_for_new_inode() - create an encryption context for a new inode | |
709 | * @ctx: where context should be written | |
710 | * @inode: inode from which to fetch policy and nonce | |
711 | * | |
712 | * Given an in-core "prepared" (via fscrypt_prepare_new_inode) inode, | |
713 | * generate a new context and write it to ctx. ctx _must_ be at least | |
714 | * FSCRYPT_SET_CONTEXT_MAX_SIZE bytes. | |
715 | * | |
716 | * Return: size of the resulting context or a negative error code. | |
717 | */ | |
718 | int fscrypt_context_for_new_inode(void *ctx, struct inode *inode) | |
719 | { | |
720 | struct fscrypt_info *ci = inode->i_crypt_info; | |
721 | ||
722 | BUILD_BUG_ON(sizeof(union fscrypt_context) != | |
723 | FSCRYPT_SET_CONTEXT_MAX_SIZE); | |
724 | ||
725 | /* fscrypt_prepare_new_inode() should have set up the key already. */ | |
726 | if (WARN_ON_ONCE(!ci)) | |
727 | return -ENOKEY; | |
728 | ||
729 | return fscrypt_new_context(ctx, &ci->ci_policy, ci->ci_nonce); | |
730 | } | |
731 | EXPORT_SYMBOL_GPL(fscrypt_context_for_new_inode); | |
732 | ||
a992b20c EB |
733 | /** |
734 | * fscrypt_set_context() - Set the fscrypt context of a new inode | |
735 | * @inode: a new inode | |
736 | * @fs_data: private data given by FS and passed to ->set_context() | |
737 | * | |
738 | * This should be called after fscrypt_prepare_new_inode(), generally during a | |
739 | * filesystem transaction. Everything here must be %GFP_NOFS-safe. | |
740 | * | |
741 | * Return: 0 on success, -errno on failure | |
742 | */ | |
743 | int fscrypt_set_context(struct inode *inode, void *fs_data) | |
744 | { | |
745 | struct fscrypt_info *ci = inode->i_crypt_info; | |
746 | union fscrypt_context ctx; | |
747 | int ctxsize; | |
748 | ||
637fa738 JL |
749 | ctxsize = fscrypt_context_for_new_inode(&ctx, inode); |
750 | if (ctxsize < 0) | |
751 | return ctxsize; | |
a992b20c EB |
752 | |
753 | /* | |
754 | * This may be the first time the inode number is available, so do any | |
755 | * delayed key setup that requires the inode number. | |
756 | */ | |
757 | if (ci->ci_policy.version == FSCRYPT_POLICY_V2 && | |
d7e7b9af EB |
758 | (ci->ci_policy.v2.flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) |
759 | fscrypt_hash_inode_number(ci, ci->ci_master_key); | |
a992b20c EB |
760 | |
761 | return inode->i_sb->s_cop->set_context(inode, &ctx, ctxsize, fs_data); | |
762 | } | |
763 | EXPORT_SYMBOL_GPL(fscrypt_set_context); | |
764 | ||
ed318a6c | 765 | /** |
218d921b EB |
766 | * fscrypt_parse_test_dummy_encryption() - parse the test_dummy_encryption mount option |
767 | * @param: the mount option | |
768 | * @dummy_policy: (input/output) the place to write the dummy policy that will | |
769 | * result from parsing the option. Zero-initialize this. If a policy is | |
770 | * already set here (due to test_dummy_encryption being given multiple | |
771 | * times), then this function will verify that the policies are the same. | |
ed318a6c | 772 | * |
218d921b EB |
773 | * Return: 0 on success; -EINVAL if the argument is invalid; -EEXIST if the |
774 | * argument conflicts with one already specified; or -ENOMEM. | |
ed318a6c | 775 | */ |
218d921b EB |
776 | int fscrypt_parse_test_dummy_encryption(const struct fs_parameter *param, |
777 | struct fscrypt_dummy_policy *dummy_policy) | |
ed318a6c | 778 | { |
218d921b EB |
779 | const char *arg = "v2"; |
780 | union fscrypt_policy *policy; | |
ed318a6c EB |
781 | int err; |
782 | ||
218d921b EB |
783 | if (param->type == fs_value_is_string && *param->string) |
784 | arg = param->string; | |
ed318a6c | 785 | |
ac4acb1f | 786 | policy = kzalloc(sizeof(*policy), GFP_KERNEL); |
218d921b EB |
787 | if (!policy) |
788 | return -ENOMEM; | |
ed318a6c | 789 | |
218d921b EB |
790 | if (!strcmp(arg, "v1")) { |
791 | policy->version = FSCRYPT_POLICY_V1; | |
ac4acb1f EB |
792 | policy->v1.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS; |
793 | policy->v1.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS; | |
218d921b | 794 | memset(policy->v1.master_key_descriptor, 0x42, |
ed318a6c | 795 | FSCRYPT_KEY_DESCRIPTOR_SIZE); |
218d921b EB |
796 | } else if (!strcmp(arg, "v2")) { |
797 | policy->version = FSCRYPT_POLICY_V2; | |
ac4acb1f EB |
798 | policy->v2.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS; |
799 | policy->v2.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS; | |
218d921b EB |
800 | err = fscrypt_get_test_dummy_key_identifier( |
801 | policy->v2.master_key_identifier); | |
802 | if (err) | |
803 | goto out; | |
804 | } else { | |
ed318a6c EB |
805 | err = -EINVAL; |
806 | goto out; | |
807 | } | |
ac4acb1f EB |
808 | |
809 | if (dummy_policy->policy) { | |
810 | if (fscrypt_policies_equal(policy, dummy_policy->policy)) | |
811 | err = 0; | |
812 | else | |
813 | err = -EEXIST; | |
814 | goto out; | |
815 | } | |
816 | dummy_policy->policy = policy; | |
817 | policy = NULL; | |
ed318a6c EB |
818 | err = 0; |
819 | out: | |
ac4acb1f | 820 | kfree(policy); |
ed318a6c EB |
821 | return err; |
822 | } | |
218d921b EB |
823 | EXPORT_SYMBOL_GPL(fscrypt_parse_test_dummy_encryption); |
824 | ||
825 | /** | |
826 | * fscrypt_dummy_policies_equal() - check whether two dummy policies are equal | |
827 | * @p1: the first test dummy policy (may be unset) | |
828 | * @p2: the second test dummy policy (may be unset) | |
829 | * | |
830 | * Return: %true if the dummy policies are both set and equal, or both unset. | |
831 | */ | |
832 | bool fscrypt_dummy_policies_equal(const struct fscrypt_dummy_policy *p1, | |
833 | const struct fscrypt_dummy_policy *p2) | |
834 | { | |
835 | if (!p1->policy && !p2->policy) | |
836 | return true; | |
837 | if (!p1->policy || !p2->policy) | |
838 | return false; | |
839 | return fscrypt_policies_equal(p1->policy, p2->policy); | |
840 | } | |
841 | EXPORT_SYMBOL_GPL(fscrypt_dummy_policies_equal); | |
842 | ||
ed318a6c EB |
843 | /** |
844 | * fscrypt_show_test_dummy_encryption() - show '-o test_dummy_encryption' | |
845 | * @seq: the seq_file to print the option to | |
846 | * @sep: the separator character to use | |
847 | * @sb: the filesystem whose options are being shown | |
848 | * | |
849 | * Show the test_dummy_encryption mount option, if it was specified. | |
850 | * This is mainly used for /proc/mounts. | |
851 | */ | |
852 | void fscrypt_show_test_dummy_encryption(struct seq_file *seq, char sep, | |
853 | struct super_block *sb) | |
854 | { | |
ac4acb1f EB |
855 | const union fscrypt_policy *policy = fscrypt_get_dummy_policy(sb); |
856 | int vers; | |
ed318a6c | 857 | |
ac4acb1f | 858 | if (!policy) |
ed318a6c | 859 | return; |
ac4acb1f EB |
860 | |
861 | vers = policy->version; | |
862 | if (vers == FSCRYPT_POLICY_V1) /* Handle numbering quirk */ | |
863 | vers = 1; | |
864 | ||
865 | seq_printf(seq, "%ctest_dummy_encryption=v%d", sep, vers); | |
ed318a6c EB |
866 | } |
867 | EXPORT_SYMBOL_GPL(fscrypt_show_test_dummy_encryption); |