xref: /openbmc/linux/crypto/api.c (revision 8365a898) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Scatterlist Cryptographic API.
4  *
5  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
6  * Copyright (c) 2002 David S. Miller (davem@redhat.com)
7  * Copyright (c) 2005 Herbert Xu <herbert@gondor.apana.org.au>
8  *
9  * Portions derived from Cryptoapi, by Alexander Kjeldaas <astor@fast.no>
10  * and Nettle, by Niels Möller.
11  */
12 
13 #include <linux/err.h>
14 #include <linux/errno.h>
15 #include <linux/kernel.h>
16 #include <linux/kmod.h>
17 #include <linux/module.h>
18 #include <linux/param.h>
19 #include <linux/sched/signal.h>
20 #include <linux/slab.h>
21 #include <linux/string.h>
22 #include <linux/completion.h>
23 #include "internal.h"
24 
25 LIST_HEAD(crypto_alg_list);
26 EXPORT_SYMBOL_GPL(crypto_alg_list);
27 DECLARE_RWSEM(crypto_alg_sem);
28 EXPORT_SYMBOL_GPL(crypto_alg_sem);
29 
30 BLOCKING_NOTIFIER_HEAD(crypto_chain);
31 EXPORT_SYMBOL_GPL(crypto_chain);
32 
33 static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg);
34 
35 struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)
36 {
37 	return try_module_get(alg->cra_module) ? crypto_alg_get(alg) : NULL;
38 }
39 EXPORT_SYMBOL_GPL(crypto_mod_get);
40 
41 void crypto_mod_put(struct crypto_alg *alg)
42 {
43 	struct module *module = alg->cra_module;
44 
45 	crypto_alg_put(alg);
46 	module_put(module);
47 }
48 EXPORT_SYMBOL_GPL(crypto_mod_put);
49 
50 static inline int crypto_is_test_larval(struct crypto_larval *larval)
51 {
52 	return larval->alg.cra_driver_name[0];
53 }
54 
55 static struct crypto_alg *__crypto_alg_lookup(const char *name, u32 type,
56 					      u32 mask)
57 {
58 	struct crypto_alg *q, *alg = NULL;
59 	int best = -2;
60 
61 	list_for_each_entry(q, &crypto_alg_list, cra_list) {
62 		int exact, fuzzy;
63 
64 		if (crypto_is_moribund(q))
65 			continue;
66 
67 		if ((q->cra_flags ^ type) & mask)
68 			continue;
69 
70 		if (crypto_is_larval(q) &&
71 		    !crypto_is_test_larval((struct crypto_larval *)q) &&
72 		    ((struct crypto_larval *)q)->mask != mask)
73 			continue;
74 
75 		exact = !strcmp(q->cra_driver_name, name);
76 		fuzzy = !strcmp(q->cra_name, name);
77 		if (!exact && !(fuzzy && q->cra_priority > best))
78 			continue;
79 
80 		if (unlikely(!crypto_mod_get(q)))
81 			continue;
82 
83 		best = q->cra_priority;
84 		if (alg)
85 			crypto_mod_put(alg);
86 		alg = q;
87 
88 		if (exact)
89 			break;
90 	}
91 
92 	return alg;
93 }
94 
95 static void crypto_larval_destroy(struct crypto_alg *alg)
96 {
97 	struct crypto_larval *larval = (void *)alg;
98 
99 	BUG_ON(!crypto_is_larval(alg));
100 	if (!IS_ERR_OR_NULL(larval->adult))
101 		crypto_mod_put(larval->adult);
102 	kfree(larval);
103 }
104 
105 struct crypto_larval *crypto_larval_alloc(const char *name, u32 type, u32 mask)
106 {
107 	struct crypto_larval *larval;
108 
109 	larval = kzalloc(sizeof(*larval), GFP_KERNEL);
110 	if (!larval)
111 		return ERR_PTR(-ENOMEM);
112 
113 	larval->mask = mask;
114 	larval->alg.cra_flags = CRYPTO_ALG_LARVAL | type;
115 	larval->alg.cra_priority = -1;
116 	larval->alg.cra_destroy = crypto_larval_destroy;
117 
118 	strlcpy(larval->alg.cra_name, name, CRYPTO_MAX_ALG_NAME);
119 	init_completion(&larval->completion);
120 
121 	return larval;
122 }
123 EXPORT_SYMBOL_GPL(crypto_larval_alloc);
124 
125 static struct crypto_alg *crypto_larval_add(const char *name, u32 type,
126 					    u32 mask)
127 {
128 	struct crypto_alg *alg;
129 	struct crypto_larval *larval;
130 
131 	larval = crypto_larval_alloc(name, type, mask);
132 	if (IS_ERR(larval))
133 		return ERR_CAST(larval);
134 
135 	refcount_set(&larval->alg.cra_refcnt, 2);
136 
137 	down_write(&crypto_alg_sem);
138 	alg = __crypto_alg_lookup(name, type, mask);
139 	if (!alg) {
140 		alg = &larval->alg;
141 		list_add(&alg->cra_list, &crypto_alg_list);
142 	}
143 	up_write(&crypto_alg_sem);
144 
145 	if (alg != &larval->alg) {
146 		kfree(larval);
147 		if (crypto_is_larval(alg))
148 			alg = crypto_larval_wait(alg);
149 	}
150 
151 	return alg;
152 }
153 
154 void crypto_larval_kill(struct crypto_alg *alg)
155 {
156 	struct crypto_larval *larval = (void *)alg;
157 
158 	down_write(&crypto_alg_sem);
159 	list_del(&alg->cra_list);
160 	up_write(&crypto_alg_sem);
161 	complete_all(&larval->completion);
162 	crypto_alg_put(alg);
163 }
164 EXPORT_SYMBOL_GPL(crypto_larval_kill);
165 
166 static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg)
167 {
168 	struct crypto_larval *larval = (void *)alg;
169 	long timeout;
170 
171 	timeout = wait_for_completion_killable_timeout(
172 		&larval->completion, 60 * HZ);
173 
174 	alg = larval->adult;
175 	if (timeout < 0)
176 		alg = ERR_PTR(-EINTR);
177 	else if (!timeout)
178 		alg = ERR_PTR(-ETIMEDOUT);
179 	else if (!alg)
180 		alg = ERR_PTR(-ENOENT);
181 	else if (IS_ERR(alg))
182 		;
183 	else if (crypto_is_test_larval(larval) &&
184 		 !(alg->cra_flags & CRYPTO_ALG_TESTED))
185 		alg = ERR_PTR(-EAGAIN);
186 	else if (!crypto_mod_get(alg))
187 		alg = ERR_PTR(-EAGAIN);
188 	crypto_mod_put(&larval->alg);
189 
190 	return alg;
191 }
192 
193 static struct crypto_alg *crypto_alg_lookup(const char *name, u32 type,
194 					    u32 mask)
195 {
196 	struct crypto_alg *alg;
197 	u32 test = 0;
198 
199 	if (!((type | mask) & CRYPTO_ALG_TESTED))
200 		test |= CRYPTO_ALG_TESTED;
201 
202 	down_read(&crypto_alg_sem);
203 	alg = __crypto_alg_lookup(name, type | test, mask | test);
204 	if (!alg && test) {
205 		alg = __crypto_alg_lookup(name, type, mask);
206 		if (alg && !crypto_is_larval(alg)) {
207 			/* Test failed */
208 			crypto_mod_put(alg);
209 			alg = ERR_PTR(-ELIBBAD);
210 		}
211 	}
212 	up_read(&crypto_alg_sem);
213 
214 	return alg;
215 }
216 
217 static struct crypto_alg *crypto_larval_lookup(const char *name, u32 type,
218 					       u32 mask)
219 {
220 	struct crypto_alg *alg;
221 
222 	if (!name)
223 		return ERR_PTR(-ENOENT);
224 
225 	type &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
226 	mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
227 
228 	alg = crypto_alg_lookup(name, type, mask);
229 	if (!alg && !(mask & CRYPTO_NOLOAD)) {
230 		request_module("crypto-%s", name);
231 
232 		if (!((type ^ CRYPTO_ALG_NEED_FALLBACK) & mask &
233 		      CRYPTO_ALG_NEED_FALLBACK))
234 			request_module("crypto-%s-all", name);
235 
236 		alg = crypto_alg_lookup(name, type, mask);
237 	}
238 
239 	if (!IS_ERR_OR_NULL(alg) && crypto_is_larval(alg))
240 		alg = crypto_larval_wait(alg);
241 	else if (!alg)
242 		alg = crypto_larval_add(name, type, mask);
243 
244 	return alg;
245 }
246 
247 int crypto_probing_notify(unsigned long val, void *v)
248 {
249 	int ok;
250 
251 	ok = blocking_notifier_call_chain(&crypto_chain, val, v);
252 	if (ok == NOTIFY_DONE) {
253 		request_module("cryptomgr");
254 		ok = blocking_notifier_call_chain(&crypto_chain, val, v);
255 	}
256 
257 	return ok;
258 }
259 EXPORT_SYMBOL_GPL(crypto_probing_notify);
260 
261 struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
262 {
263 	struct crypto_alg *alg;
264 	struct crypto_alg *larval;
265 	int ok;
266 
267 	/*
268 	 * If the internal flag is set for a cipher, require a caller to
269 	 * to invoke the cipher with the internal flag to use that cipher.
270 	 * Also, if a caller wants to allocate a cipher that may or may
271 	 * not be an internal cipher, use type | CRYPTO_ALG_INTERNAL and
272 	 * !(mask & CRYPTO_ALG_INTERNAL).
273 	 */
274 	if (!((type | mask) & CRYPTO_ALG_INTERNAL))
275 		mask |= CRYPTO_ALG_INTERNAL;
276 
277 	larval = crypto_larval_lookup(name, type, mask);
278 	if (IS_ERR(larval) || !crypto_is_larval(larval))
279 		return larval;
280 
281 	ok = crypto_probing_notify(CRYPTO_MSG_ALG_REQUEST, larval);
282 
283 	if (ok == NOTIFY_STOP)
284 		alg = crypto_larval_wait(larval);
285 	else {
286 		crypto_mod_put(larval);
287 		alg = ERR_PTR(-ENOENT);
288 	}
289 	crypto_larval_kill(larval);
290 	return alg;
291 }
292 EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
293 
294 static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
295 {
296 	const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
297 
298 	if (type_obj)
299 		return type_obj->init(tfm, type, mask);
300 	return 0;
301 }
302 
303 static void crypto_exit_ops(struct crypto_tfm *tfm)
304 {
305 	const struct crypto_type *type = tfm->__crt_alg->cra_type;
306 
307 	if (type && tfm->exit)
308 		tfm->exit(tfm);
309 }
310 
311 static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
312 {
313 	const struct crypto_type *type_obj = alg->cra_type;
314 	unsigned int len;
315 
316 	len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
317 	if (type_obj)
318 		return len + type_obj->ctxsize(alg, type, mask);
319 
320 	switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
321 	default:
322 		BUG();
323 
324 	case CRYPTO_ALG_TYPE_CIPHER:
325 		len += crypto_cipher_ctxsize(alg);
326 		break;
327 
328 	case CRYPTO_ALG_TYPE_COMPRESS:
329 		len += crypto_compress_ctxsize(alg);
330 		break;
331 	}
332 
333 	return len;
334 }
335 
336 void crypto_shoot_alg(struct crypto_alg *alg)
337 {
338 	down_write(&crypto_alg_sem);
339 	alg->cra_flags |= CRYPTO_ALG_DYING;
340 	up_write(&crypto_alg_sem);
341 }
342 EXPORT_SYMBOL_GPL(crypto_shoot_alg);
343 
344 struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
345 				      u32 mask)
346 {
347 	struct crypto_tfm *tfm = NULL;
348 	unsigned int tfm_size;
349 	int err = -ENOMEM;
350 
351 	tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
352 	tfm = kzalloc(tfm_size, GFP_KERNEL);
353 	if (tfm == NULL)
354 		goto out_err;
355 
356 	tfm->__crt_alg = alg;
357 
358 	err = crypto_init_ops(tfm, type, mask);
359 	if (err)
360 		goto out_free_tfm;
361 
362 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
363 		goto cra_init_failed;
364 
365 	goto out;
366 
367 cra_init_failed:
368 	crypto_exit_ops(tfm);
369 out_free_tfm:
370 	if (err == -EAGAIN)
371 		crypto_shoot_alg(alg);
372 	kfree(tfm);
373 out_err:
374 	tfm = ERR_PTR(err);
375 out:
376 	return tfm;
377 }
378 EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
379 
380 /*
381  *	crypto_alloc_base - Locate algorithm and allocate transform
382  *	@alg_name: Name of algorithm
383  *	@type: Type of algorithm
384  *	@mask: Mask for type comparison
385  *
386  *	This function should not be used by new algorithm types.
387  *	Please use crypto_alloc_tfm instead.
388  *
389  *	crypto_alloc_base() will first attempt to locate an already loaded
390  *	algorithm.  If that fails and the kernel supports dynamically loadable
391  *	modules, it will then attempt to load a module of the same name or
392  *	alias.  If that fails it will send a query to any loaded crypto manager
393  *	to construct an algorithm on the fly.  A refcount is grabbed on the
394  *	algorithm which is then associated with the new transform.
395  *
396  *	The returned transform is of a non-determinate type.  Most people
397  *	should use one of the more specific allocation functions such as
398  *	crypto_alloc_skcipher().
399  *
400  *	In case of error the return value is an error pointer.
401  */
402 struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
403 {
404 	struct crypto_tfm *tfm;
405 	int err;
406 
407 	for (;;) {
408 		struct crypto_alg *alg;
409 
410 		alg = crypto_alg_mod_lookup(alg_name, type, mask);
411 		if (IS_ERR(alg)) {
412 			err = PTR_ERR(alg);
413 			goto err;
414 		}
415 
416 		tfm = __crypto_alloc_tfm(alg, type, mask);
417 		if (!IS_ERR(tfm))
418 			return tfm;
419 
420 		crypto_mod_put(alg);
421 		err = PTR_ERR(tfm);
422 
423 err:
424 		if (err != -EAGAIN)
425 			break;
426 		if (fatal_signal_pending(current)) {
427 			err = -EINTR;
428 			break;
429 		}
430 	}
431 
432 	return ERR_PTR(err);
433 }
434 EXPORT_SYMBOL_GPL(crypto_alloc_base);
435 
436 void *crypto_create_tfm(struct crypto_alg *alg,
437 			const struct crypto_type *frontend)
438 {
439 	char *mem;
440 	struct crypto_tfm *tfm = NULL;
441 	unsigned int tfmsize;
442 	unsigned int total;
443 	int err = -ENOMEM;
444 
445 	tfmsize = frontend->tfmsize;
446 	total = tfmsize + sizeof(*tfm) + frontend->extsize(alg);
447 
448 	mem = kzalloc(total, GFP_KERNEL);
449 	if (mem == NULL)
450 		goto out_err;
451 
452 	tfm = (struct crypto_tfm *)(mem + tfmsize);
453 	tfm->__crt_alg = alg;
454 
455 	err = frontend->init_tfm(tfm);
456 	if (err)
457 		goto out_free_tfm;
458 
459 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
460 		goto cra_init_failed;
461 
462 	goto out;
463 
464 cra_init_failed:
465 	crypto_exit_ops(tfm);
466 out_free_tfm:
467 	if (err == -EAGAIN)
468 		crypto_shoot_alg(alg);
469 	kfree(mem);
470 out_err:
471 	mem = ERR_PTR(err);
472 out:
473 	return mem;
474 }
475 EXPORT_SYMBOL_GPL(crypto_create_tfm);
476 
477 struct crypto_alg *crypto_find_alg(const char *alg_name,
478 				   const struct crypto_type *frontend,
479 				   u32 type, u32 mask)
480 {
481 	if (frontend) {
482 		type &= frontend->maskclear;
483 		mask &= frontend->maskclear;
484 		type |= frontend->type;
485 		mask |= frontend->maskset;
486 	}
487 
488 	return crypto_alg_mod_lookup(alg_name, type, mask);
489 }
490 EXPORT_SYMBOL_GPL(crypto_find_alg);
491 
492 /*
493  *	crypto_alloc_tfm - Locate algorithm and allocate transform
494  *	@alg_name: Name of algorithm
495  *	@frontend: Frontend algorithm type
496  *	@type: Type of algorithm
497  *	@mask: Mask for type comparison
498  *
499  *	crypto_alloc_tfm() will first attempt to locate an already loaded
500  *	algorithm.  If that fails and the kernel supports dynamically loadable
501  *	modules, it will then attempt to load a module of the same name or
502  *	alias.  If that fails it will send a query to any loaded crypto manager
503  *	to construct an algorithm on the fly.  A refcount is grabbed on the
504  *	algorithm which is then associated with the new transform.
505  *
506  *	The returned transform is of a non-determinate type.  Most people
507  *	should use one of the more specific allocation functions such as
508  *	crypto_alloc_skcipher().
509  *
510  *	In case of error the return value is an error pointer.
511  */
512 void *crypto_alloc_tfm(const char *alg_name,
513 		       const struct crypto_type *frontend, u32 type, u32 mask)
514 {
515 	void *tfm;
516 	int err;
517 
518 	for (;;) {
519 		struct crypto_alg *alg;
520 
521 		alg = crypto_find_alg(alg_name, frontend, type, mask);
522 		if (IS_ERR(alg)) {
523 			err = PTR_ERR(alg);
524 			goto err;
525 		}
526 
527 		tfm = crypto_create_tfm(alg, frontend);
528 		if (!IS_ERR(tfm))
529 			return tfm;
530 
531 		crypto_mod_put(alg);
532 		err = PTR_ERR(tfm);
533 
534 err:
535 		if (err != -EAGAIN)
536 			break;
537 		if (fatal_signal_pending(current)) {
538 			err = -EINTR;
539 			break;
540 		}
541 	}
542 
543 	return ERR_PTR(err);
544 }
545 EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
546 
547 /*
548  *	crypto_destroy_tfm - Free crypto transform
549  *	@mem: Start of tfm slab
550  *	@tfm: Transform to free
551  *
552  *	This function frees up the transform and any associated resources,
553  *	then drops the refcount on the associated algorithm.
554  */
555 void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
556 {
557 	struct crypto_alg *alg;
558 
559 	if (unlikely(!mem))
560 		return;
561 
562 	alg = tfm->__crt_alg;
563 
564 	if (!tfm->exit && alg->cra_exit)
565 		alg->cra_exit(tfm);
566 	crypto_exit_ops(tfm);
567 	crypto_mod_put(alg);
568 	kzfree(mem);
569 }
570 EXPORT_SYMBOL_GPL(crypto_destroy_tfm);
571 
572 int crypto_has_alg(const char *name, u32 type, u32 mask)
573 {
574 	int ret = 0;
575 	struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
576 
577 	if (!IS_ERR(alg)) {
578 		crypto_mod_put(alg);
579 		ret = 1;
580 	}
581 
582 	return ret;
583 }
584 EXPORT_SYMBOL_GPL(crypto_has_alg);
585 
586 void crypto_req_done(struct crypto_async_request *req, int err)
587 {
588 	struct crypto_wait *wait = req->data;
589 
590 	if (err == -EINPROGRESS)
591 		return;
592 
593 	wait->err = err;
594 	complete(&wait->completion);
595 }
596 EXPORT_SYMBOL_GPL(crypto_req_done);
597 
598 MODULE_DESCRIPTION("Cryptographic core API");
599 MODULE_LICENSE("GPL");
600 MODULE_SOFTDEP("pre: cryptomgr");
601