xref: /openbmc/linux/crypto/api.c (revision b593bce5)
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 (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 (crypto_is_test_larval(larval) &&
182 		 !(alg->cra_flags & CRYPTO_ALG_TESTED))
183 		alg = ERR_PTR(-EAGAIN);
184 	else if (!crypto_mod_get(alg))
185 		alg = ERR_PTR(-EAGAIN);
186 	crypto_mod_put(&larval->alg);
187 
188 	return alg;
189 }
190 
191 static struct crypto_alg *crypto_alg_lookup(const char *name, u32 type,
192 					    u32 mask)
193 {
194 	struct crypto_alg *alg;
195 	u32 test = 0;
196 
197 	if (!((type | mask) & CRYPTO_ALG_TESTED))
198 		test |= CRYPTO_ALG_TESTED;
199 
200 	down_read(&crypto_alg_sem);
201 	alg = __crypto_alg_lookup(name, type | test, mask | test);
202 	if (!alg && test) {
203 		alg = __crypto_alg_lookup(name, type, mask);
204 		if (alg && !crypto_is_larval(alg)) {
205 			/* Test failed */
206 			crypto_mod_put(alg);
207 			alg = ERR_PTR(-ELIBBAD);
208 		}
209 	}
210 	up_read(&crypto_alg_sem);
211 
212 	return alg;
213 }
214 
215 static struct crypto_alg *crypto_larval_lookup(const char *name, u32 type,
216 					       u32 mask)
217 {
218 	struct crypto_alg *alg;
219 
220 	if (!name)
221 		return ERR_PTR(-ENOENT);
222 
223 	type &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
224 	mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
225 
226 	alg = crypto_alg_lookup(name, type, mask);
227 	if (!alg && !(mask & CRYPTO_NOLOAD)) {
228 		request_module("crypto-%s", name);
229 
230 		if (!((type ^ CRYPTO_ALG_NEED_FALLBACK) & mask &
231 		      CRYPTO_ALG_NEED_FALLBACK))
232 			request_module("crypto-%s-all", name);
233 
234 		alg = crypto_alg_lookup(name, type, mask);
235 	}
236 
237 	if (!IS_ERR_OR_NULL(alg) && crypto_is_larval(alg))
238 		alg = crypto_larval_wait(alg);
239 	else if (!alg)
240 		alg = crypto_larval_add(name, type, mask);
241 
242 	return alg;
243 }
244 
245 int crypto_probing_notify(unsigned long val, void *v)
246 {
247 	int ok;
248 
249 	ok = blocking_notifier_call_chain(&crypto_chain, val, v);
250 	if (ok == NOTIFY_DONE) {
251 		request_module("cryptomgr");
252 		ok = blocking_notifier_call_chain(&crypto_chain, val, v);
253 	}
254 
255 	return ok;
256 }
257 EXPORT_SYMBOL_GPL(crypto_probing_notify);
258 
259 struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
260 {
261 	struct crypto_alg *alg;
262 	struct crypto_alg *larval;
263 	int ok;
264 
265 	/*
266 	 * If the internal flag is set for a cipher, require a caller to
267 	 * to invoke the cipher with the internal flag to use that cipher.
268 	 * Also, if a caller wants to allocate a cipher that may or may
269 	 * not be an internal cipher, use type | CRYPTO_ALG_INTERNAL and
270 	 * !(mask & CRYPTO_ALG_INTERNAL).
271 	 */
272 	if (!((type | mask) & CRYPTO_ALG_INTERNAL))
273 		mask |= CRYPTO_ALG_INTERNAL;
274 
275 	larval = crypto_larval_lookup(name, type, mask);
276 	if (IS_ERR(larval) || !crypto_is_larval(larval))
277 		return larval;
278 
279 	ok = crypto_probing_notify(CRYPTO_MSG_ALG_REQUEST, larval);
280 
281 	if (ok == NOTIFY_STOP)
282 		alg = crypto_larval_wait(larval);
283 	else {
284 		crypto_mod_put(larval);
285 		alg = ERR_PTR(-ENOENT);
286 	}
287 	crypto_larval_kill(larval);
288 	return alg;
289 }
290 EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
291 
292 static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
293 {
294 	const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
295 
296 	if (type_obj)
297 		return type_obj->init(tfm, type, mask);
298 
299 	switch (crypto_tfm_alg_type(tfm)) {
300 	case CRYPTO_ALG_TYPE_CIPHER:
301 		return crypto_init_cipher_ops(tfm);
302 
303 	case CRYPTO_ALG_TYPE_COMPRESS:
304 		return crypto_init_compress_ops(tfm);
305 
306 	default:
307 		break;
308 	}
309 
310 	BUG();
311 	return -EINVAL;
312 }
313 
314 static void crypto_exit_ops(struct crypto_tfm *tfm)
315 {
316 	const struct crypto_type *type = tfm->__crt_alg->cra_type;
317 
318 	if (type && tfm->exit)
319 		tfm->exit(tfm);
320 }
321 
322 static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
323 {
324 	const struct crypto_type *type_obj = alg->cra_type;
325 	unsigned int len;
326 
327 	len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
328 	if (type_obj)
329 		return len + type_obj->ctxsize(alg, type, mask);
330 
331 	switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
332 	default:
333 		BUG();
334 
335 	case CRYPTO_ALG_TYPE_CIPHER:
336 		len += crypto_cipher_ctxsize(alg);
337 		break;
338 
339 	case CRYPTO_ALG_TYPE_COMPRESS:
340 		len += crypto_compress_ctxsize(alg);
341 		break;
342 	}
343 
344 	return len;
345 }
346 
347 void crypto_shoot_alg(struct crypto_alg *alg)
348 {
349 	down_write(&crypto_alg_sem);
350 	alg->cra_flags |= CRYPTO_ALG_DYING;
351 	up_write(&crypto_alg_sem);
352 }
353 EXPORT_SYMBOL_GPL(crypto_shoot_alg);
354 
355 struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
356 				      u32 mask)
357 {
358 	struct crypto_tfm *tfm = NULL;
359 	unsigned int tfm_size;
360 	int err = -ENOMEM;
361 
362 	tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
363 	tfm = kzalloc(tfm_size, GFP_KERNEL);
364 	if (tfm == NULL)
365 		goto out_err;
366 
367 	tfm->__crt_alg = alg;
368 
369 	err = crypto_init_ops(tfm, type, mask);
370 	if (err)
371 		goto out_free_tfm;
372 
373 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
374 		goto cra_init_failed;
375 
376 	goto out;
377 
378 cra_init_failed:
379 	crypto_exit_ops(tfm);
380 out_free_tfm:
381 	if (err == -EAGAIN)
382 		crypto_shoot_alg(alg);
383 	kfree(tfm);
384 out_err:
385 	tfm = ERR_PTR(err);
386 out:
387 	return tfm;
388 }
389 EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
390 
391 /*
392  *	crypto_alloc_base - Locate algorithm and allocate transform
393  *	@alg_name: Name of algorithm
394  *	@type: Type of algorithm
395  *	@mask: Mask for type comparison
396  *
397  *	This function should not be used by new algorithm types.
398  *	Please use crypto_alloc_tfm instead.
399  *
400  *	crypto_alloc_base() will first attempt to locate an already loaded
401  *	algorithm.  If that fails and the kernel supports dynamically loadable
402  *	modules, it will then attempt to load a module of the same name or
403  *	alias.  If that fails it will send a query to any loaded crypto manager
404  *	to construct an algorithm on the fly.  A refcount is grabbed on the
405  *	algorithm which is then associated with the new transform.
406  *
407  *	The returned transform is of a non-determinate type.  Most people
408  *	should use one of the more specific allocation functions such as
409  *	crypto_alloc_blkcipher.
410  *
411  *	In case of error the return value is an error pointer.
412  */
413 struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
414 {
415 	struct crypto_tfm *tfm;
416 	int err;
417 
418 	for (;;) {
419 		struct crypto_alg *alg;
420 
421 		alg = crypto_alg_mod_lookup(alg_name, type, mask);
422 		if (IS_ERR(alg)) {
423 			err = PTR_ERR(alg);
424 			goto err;
425 		}
426 
427 		tfm = __crypto_alloc_tfm(alg, type, mask);
428 		if (!IS_ERR(tfm))
429 			return tfm;
430 
431 		crypto_mod_put(alg);
432 		err = PTR_ERR(tfm);
433 
434 err:
435 		if (err != -EAGAIN)
436 			break;
437 		if (fatal_signal_pending(current)) {
438 			err = -EINTR;
439 			break;
440 		}
441 	}
442 
443 	return ERR_PTR(err);
444 }
445 EXPORT_SYMBOL_GPL(crypto_alloc_base);
446 
447 void *crypto_create_tfm(struct crypto_alg *alg,
448 			const struct crypto_type *frontend)
449 {
450 	char *mem;
451 	struct crypto_tfm *tfm = NULL;
452 	unsigned int tfmsize;
453 	unsigned int total;
454 	int err = -ENOMEM;
455 
456 	tfmsize = frontend->tfmsize;
457 	total = tfmsize + sizeof(*tfm) + frontend->extsize(alg);
458 
459 	mem = kzalloc(total, GFP_KERNEL);
460 	if (mem == NULL)
461 		goto out_err;
462 
463 	tfm = (struct crypto_tfm *)(mem + tfmsize);
464 	tfm->__crt_alg = alg;
465 
466 	err = frontend->init_tfm(tfm);
467 	if (err)
468 		goto out_free_tfm;
469 
470 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
471 		goto cra_init_failed;
472 
473 	goto out;
474 
475 cra_init_failed:
476 	crypto_exit_ops(tfm);
477 out_free_tfm:
478 	if (err == -EAGAIN)
479 		crypto_shoot_alg(alg);
480 	kfree(mem);
481 out_err:
482 	mem = ERR_PTR(err);
483 out:
484 	return mem;
485 }
486 EXPORT_SYMBOL_GPL(crypto_create_tfm);
487 
488 struct crypto_alg *crypto_find_alg(const char *alg_name,
489 				   const struct crypto_type *frontend,
490 				   u32 type, u32 mask)
491 {
492 	if (frontend) {
493 		type &= frontend->maskclear;
494 		mask &= frontend->maskclear;
495 		type |= frontend->type;
496 		mask |= frontend->maskset;
497 	}
498 
499 	return crypto_alg_mod_lookup(alg_name, type, mask);
500 }
501 EXPORT_SYMBOL_GPL(crypto_find_alg);
502 
503 /*
504  *	crypto_alloc_tfm - Locate algorithm and allocate transform
505  *	@alg_name: Name of algorithm
506  *	@frontend: Frontend algorithm type
507  *	@type: Type of algorithm
508  *	@mask: Mask for type comparison
509  *
510  *	crypto_alloc_tfm() will first attempt to locate an already loaded
511  *	algorithm.  If that fails and the kernel supports dynamically loadable
512  *	modules, it will then attempt to load a module of the same name or
513  *	alias.  If that fails it will send a query to any loaded crypto manager
514  *	to construct an algorithm on the fly.  A refcount is grabbed on the
515  *	algorithm which is then associated with the new transform.
516  *
517  *	The returned transform is of a non-determinate type.  Most people
518  *	should use one of the more specific allocation functions such as
519  *	crypto_alloc_blkcipher.
520  *
521  *	In case of error the return value is an error pointer.
522  */
523 void *crypto_alloc_tfm(const char *alg_name,
524 		       const struct crypto_type *frontend, u32 type, u32 mask)
525 {
526 	void *tfm;
527 	int err;
528 
529 	for (;;) {
530 		struct crypto_alg *alg;
531 
532 		alg = crypto_find_alg(alg_name, frontend, type, mask);
533 		if (IS_ERR(alg)) {
534 			err = PTR_ERR(alg);
535 			goto err;
536 		}
537 
538 		tfm = crypto_create_tfm(alg, frontend);
539 		if (!IS_ERR(tfm))
540 			return tfm;
541 
542 		crypto_mod_put(alg);
543 		err = PTR_ERR(tfm);
544 
545 err:
546 		if (err != -EAGAIN)
547 			break;
548 		if (fatal_signal_pending(current)) {
549 			err = -EINTR;
550 			break;
551 		}
552 	}
553 
554 	return ERR_PTR(err);
555 }
556 EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
557 
558 /*
559  *	crypto_destroy_tfm - Free crypto transform
560  *	@mem: Start of tfm slab
561  *	@tfm: Transform to free
562  *
563  *	This function frees up the transform and any associated resources,
564  *	then drops the refcount on the associated algorithm.
565  */
566 void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
567 {
568 	struct crypto_alg *alg;
569 
570 	if (unlikely(!mem))
571 		return;
572 
573 	alg = tfm->__crt_alg;
574 
575 	if (!tfm->exit && alg->cra_exit)
576 		alg->cra_exit(tfm);
577 	crypto_exit_ops(tfm);
578 	crypto_mod_put(alg);
579 	kzfree(mem);
580 }
581 EXPORT_SYMBOL_GPL(crypto_destroy_tfm);
582 
583 int crypto_has_alg(const char *name, u32 type, u32 mask)
584 {
585 	int ret = 0;
586 	struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
587 
588 	if (!IS_ERR(alg)) {
589 		crypto_mod_put(alg);
590 		ret = 1;
591 	}
592 
593 	return ret;
594 }
595 EXPORT_SYMBOL_GPL(crypto_has_alg);
596 
597 void crypto_req_done(struct crypto_async_request *req, int err)
598 {
599 	struct crypto_wait *wait = req->data;
600 
601 	if (err == -EINPROGRESS)
602 		return;
603 
604 	wait->err = err;
605 	complete(&wait->completion);
606 }
607 EXPORT_SYMBOL_GPL(crypto_req_done);
608 
609 MODULE_DESCRIPTION("Cryptographic core API");
610 MODULE_LICENSE("GPL");
611