xref: /openbmc/linux/crypto/api.c (revision 78c99ba1) 
1 /*
2  * Scatterlist Cryptographic API.
3  *
4  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
5  * Copyright (c) 2002 David S. Miller (davem@redhat.com)
6  * Copyright (c) 2005 Herbert Xu <herbert@gondor.apana.org.au>
7  *
8  * Portions derived from Cryptoapi, by Alexander Kjeldaas <astor@fast.no>
9  * and Nettle, by Niels Möller.
10  *
11  * This program is free software; you can redistribute it and/or modify it
12  * under the terms of the GNU General Public License as published by the Free
13  * Software Foundation; either version 2 of the License, or (at your option)
14  * any later version.
15  *
16  */
17 
18 #include <linux/err.h>
19 #include <linux/errno.h>
20 #include <linux/kernel.h>
21 #include <linux/kmod.h>
22 #include <linux/module.h>
23 #include <linux/param.h>
24 #include <linux/sched.h>
25 #include <linux/slab.h>
26 #include <linux/string.h>
27 #include "internal.h"
28 
29 LIST_HEAD(crypto_alg_list);
30 EXPORT_SYMBOL_GPL(crypto_alg_list);
31 DECLARE_RWSEM(crypto_alg_sem);
32 EXPORT_SYMBOL_GPL(crypto_alg_sem);
33 
34 BLOCKING_NOTIFIER_HEAD(crypto_chain);
35 EXPORT_SYMBOL_GPL(crypto_chain);
36 
37 static inline struct crypto_alg *crypto_alg_get(struct crypto_alg *alg)
38 {
39 	atomic_inc(&alg->cra_refcnt);
40 	return alg;
41 }
42 
43 struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)
44 {
45 	return try_module_get(alg->cra_module) ? crypto_alg_get(alg) : NULL;
46 }
47 EXPORT_SYMBOL_GPL(crypto_mod_get);
48 
49 void crypto_mod_put(struct crypto_alg *alg)
50 {
51 	struct module *module = alg->cra_module;
52 
53 	crypto_alg_put(alg);
54 	module_put(module);
55 }
56 EXPORT_SYMBOL_GPL(crypto_mod_put);
57 
58 static inline int crypto_is_test_larval(struct crypto_larval *larval)
59 {
60 	return larval->alg.cra_driver_name[0];
61 }
62 
63 static struct crypto_alg *__crypto_alg_lookup(const char *name, u32 type,
64 					      u32 mask)
65 {
66 	struct crypto_alg *q, *alg = NULL;
67 	int best = -2;
68 
69 	list_for_each_entry(q, &crypto_alg_list, cra_list) {
70 		int exact, fuzzy;
71 
72 		if (crypto_is_moribund(q))
73 			continue;
74 
75 		if ((q->cra_flags ^ type) & mask)
76 			continue;
77 
78 		if (crypto_is_larval(q) &&
79 		    !crypto_is_test_larval((struct crypto_larval *)q) &&
80 		    ((struct crypto_larval *)q)->mask != mask)
81 			continue;
82 
83 		exact = !strcmp(q->cra_driver_name, name);
84 		fuzzy = !strcmp(q->cra_name, name);
85 		if (!exact && !(fuzzy && q->cra_priority > best))
86 			continue;
87 
88 		if (unlikely(!crypto_mod_get(q)))
89 			continue;
90 
91 		best = q->cra_priority;
92 		if (alg)
93 			crypto_mod_put(alg);
94 		alg = q;
95 
96 		if (exact)
97 			break;
98 	}
99 
100 	return alg;
101 }
102 
103 static void crypto_larval_destroy(struct crypto_alg *alg)
104 {
105 	struct crypto_larval *larval = (void *)alg;
106 
107 	BUG_ON(!crypto_is_larval(alg));
108 	if (larval->adult)
109 		crypto_mod_put(larval->adult);
110 	kfree(larval);
111 }
112 
113 struct crypto_larval *crypto_larval_alloc(const char *name, u32 type, u32 mask)
114 {
115 	struct crypto_larval *larval;
116 
117 	larval = kzalloc(sizeof(*larval), GFP_KERNEL);
118 	if (!larval)
119 		return ERR_PTR(-ENOMEM);
120 
121 	larval->mask = mask;
122 	larval->alg.cra_flags = CRYPTO_ALG_LARVAL | type;
123 	larval->alg.cra_priority = -1;
124 	larval->alg.cra_destroy = crypto_larval_destroy;
125 
126 	strlcpy(larval->alg.cra_name, name, CRYPTO_MAX_ALG_NAME);
127 	init_completion(&larval->completion);
128 
129 	return larval;
130 }
131 EXPORT_SYMBOL_GPL(crypto_larval_alloc);
132 
133 static struct crypto_alg *crypto_larval_add(const char *name, u32 type,
134 					    u32 mask)
135 {
136 	struct crypto_alg *alg;
137 	struct crypto_larval *larval;
138 
139 	larval = crypto_larval_alloc(name, type, mask);
140 	if (IS_ERR(larval))
141 		return ERR_CAST(larval);
142 
143 	atomic_set(&larval->alg.cra_refcnt, 2);
144 
145 	down_write(&crypto_alg_sem);
146 	alg = __crypto_alg_lookup(name, type, mask);
147 	if (!alg) {
148 		alg = &larval->alg;
149 		list_add(&alg->cra_list, &crypto_alg_list);
150 	}
151 	up_write(&crypto_alg_sem);
152 
153 	if (alg != &larval->alg)
154 		kfree(larval);
155 
156 	return alg;
157 }
158 
159 void crypto_larval_kill(struct crypto_alg *alg)
160 {
161 	struct crypto_larval *larval = (void *)alg;
162 
163 	down_write(&crypto_alg_sem);
164 	list_del(&alg->cra_list);
165 	up_write(&crypto_alg_sem);
166 	complete_all(&larval->completion);
167 	crypto_alg_put(alg);
168 }
169 EXPORT_SYMBOL_GPL(crypto_larval_kill);
170 
171 static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg)
172 {
173 	struct crypto_larval *larval = (void *)alg;
174 	long timeout;
175 
176 	timeout = wait_for_completion_interruptible_timeout(
177 		&larval->completion, 60 * HZ);
178 
179 	alg = larval->adult;
180 	if (timeout < 0)
181 		alg = ERR_PTR(-EINTR);
182 	else if (!timeout)
183 		alg = ERR_PTR(-ETIMEDOUT);
184 	else if (!alg)
185 		alg = ERR_PTR(-ENOENT);
186 	else if (crypto_is_test_larval(larval) &&
187 		 !(alg->cra_flags & CRYPTO_ALG_TESTED))
188 		alg = ERR_PTR(-EAGAIN);
189 	else if (!crypto_mod_get(alg))
190 		alg = ERR_PTR(-EAGAIN);
191 	crypto_mod_put(&larval->alg);
192 
193 	return alg;
194 }
195 
196 struct crypto_alg *crypto_alg_lookup(const char *name, u32 type, u32 mask)
197 {
198 	struct crypto_alg *alg;
199 
200 	down_read(&crypto_alg_sem);
201 	alg = __crypto_alg_lookup(name, type, mask);
202 	up_read(&crypto_alg_sem);
203 
204 	return alg;
205 }
206 EXPORT_SYMBOL_GPL(crypto_alg_lookup);
207 
208 struct crypto_alg *crypto_larval_lookup(const char *name, u32 type, u32 mask)
209 {
210 	struct crypto_alg *alg;
211 
212 	if (!name)
213 		return ERR_PTR(-ENOENT);
214 
215 	mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
216 	type &= mask;
217 
218 	alg = crypto_alg_lookup(name, type, mask);
219 	if (!alg) {
220 		char tmp[CRYPTO_MAX_ALG_NAME];
221 
222 		request_module(name);
223 
224 		if (!((type ^ CRYPTO_ALG_NEED_FALLBACK) & mask &
225 		      CRYPTO_ALG_NEED_FALLBACK) &&
226 		    snprintf(tmp, sizeof(tmp), "%s-all", name) < sizeof(tmp))
227 			request_module(tmp);
228 
229 		alg = crypto_alg_lookup(name, type, mask);
230 	}
231 
232 	if (alg)
233 		return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
234 
235 	return crypto_larval_add(name, type, mask);
236 }
237 EXPORT_SYMBOL_GPL(crypto_larval_lookup);
238 
239 int crypto_probing_notify(unsigned long val, void *v)
240 {
241 	int ok;
242 
243 	ok = blocking_notifier_call_chain(&crypto_chain, val, v);
244 	if (ok == NOTIFY_DONE) {
245 		request_module("cryptomgr");
246 		ok = blocking_notifier_call_chain(&crypto_chain, val, v);
247 	}
248 
249 	return ok;
250 }
251 EXPORT_SYMBOL_GPL(crypto_probing_notify);
252 
253 struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
254 {
255 	struct crypto_alg *alg;
256 	struct crypto_alg *larval;
257 	int ok;
258 
259 	if (!((type | mask) & CRYPTO_ALG_TESTED)) {
260 		type |= CRYPTO_ALG_TESTED;
261 		mask |= CRYPTO_ALG_TESTED;
262 	}
263 
264 	larval = crypto_larval_lookup(name, type, mask);
265 	if (IS_ERR(larval) || !crypto_is_larval(larval))
266 		return larval;
267 
268 	ok = crypto_probing_notify(CRYPTO_MSG_ALG_REQUEST, larval);
269 
270 	if (ok == NOTIFY_STOP)
271 		alg = crypto_larval_wait(larval);
272 	else {
273 		crypto_mod_put(larval);
274 		alg = ERR_PTR(-ENOENT);
275 	}
276 	crypto_larval_kill(larval);
277 	return alg;
278 }
279 EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
280 
281 static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
282 {
283 	const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
284 
285 	if (type_obj)
286 		return type_obj->init(tfm, type, mask);
287 
288 	switch (crypto_tfm_alg_type(tfm)) {
289 	case CRYPTO_ALG_TYPE_CIPHER:
290 		return crypto_init_cipher_ops(tfm);
291 
292 	case CRYPTO_ALG_TYPE_DIGEST:
293 		if ((mask & CRYPTO_ALG_TYPE_HASH_MASK) !=
294 		    CRYPTO_ALG_TYPE_HASH_MASK)
295 			return crypto_init_digest_ops_async(tfm);
296 		else
297 			return crypto_init_digest_ops(tfm);
298 
299 	case CRYPTO_ALG_TYPE_COMPRESS:
300 		return crypto_init_compress_ops(tfm);
301 
302 	default:
303 		break;
304 	}
305 
306 	BUG();
307 	return -EINVAL;
308 }
309 
310 static void crypto_exit_ops(struct crypto_tfm *tfm)
311 {
312 	const struct crypto_type *type = tfm->__crt_alg->cra_type;
313 
314 	if (type) {
315 		if (tfm->exit)
316 			tfm->exit(tfm);
317 		return;
318 	}
319 
320 	switch (crypto_tfm_alg_type(tfm)) {
321 	case CRYPTO_ALG_TYPE_CIPHER:
322 		crypto_exit_cipher_ops(tfm);
323 		break;
324 
325 	case CRYPTO_ALG_TYPE_DIGEST:
326 		crypto_exit_digest_ops(tfm);
327 		break;
328 
329 	case CRYPTO_ALG_TYPE_COMPRESS:
330 		crypto_exit_compress_ops(tfm);
331 		break;
332 
333 	default:
334 		BUG();
335 
336 	}
337 }
338 
339 static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
340 {
341 	const struct crypto_type *type_obj = alg->cra_type;
342 	unsigned int len;
343 
344 	len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
345 	if (type_obj)
346 		return len + type_obj->ctxsize(alg, type, mask);
347 
348 	switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
349 	default:
350 		BUG();
351 
352 	case CRYPTO_ALG_TYPE_CIPHER:
353 		len += crypto_cipher_ctxsize(alg);
354 		break;
355 
356 	case CRYPTO_ALG_TYPE_DIGEST:
357 		len += crypto_digest_ctxsize(alg);
358 		break;
359 
360 	case CRYPTO_ALG_TYPE_COMPRESS:
361 		len += crypto_compress_ctxsize(alg);
362 		break;
363 	}
364 
365 	return len;
366 }
367 
368 void crypto_shoot_alg(struct crypto_alg *alg)
369 {
370 	down_write(&crypto_alg_sem);
371 	alg->cra_flags |= CRYPTO_ALG_DYING;
372 	up_write(&crypto_alg_sem);
373 }
374 EXPORT_SYMBOL_GPL(crypto_shoot_alg);
375 
376 struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
377 				      u32 mask)
378 {
379 	struct crypto_tfm *tfm = NULL;
380 	unsigned int tfm_size;
381 	int err = -ENOMEM;
382 
383 	tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
384 	tfm = kzalloc(tfm_size, GFP_KERNEL);
385 	if (tfm == NULL)
386 		goto out_err;
387 
388 	tfm->__crt_alg = alg;
389 
390 	err = crypto_init_ops(tfm, type, mask);
391 	if (err)
392 		goto out_free_tfm;
393 
394 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
395 		goto cra_init_failed;
396 
397 	goto out;
398 
399 cra_init_failed:
400 	crypto_exit_ops(tfm);
401 out_free_tfm:
402 	if (err == -EAGAIN)
403 		crypto_shoot_alg(alg);
404 	kfree(tfm);
405 out_err:
406 	tfm = ERR_PTR(err);
407 out:
408 	return tfm;
409 }
410 EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
411 
412 /*
413  *	crypto_alloc_base - Locate algorithm and allocate transform
414  *	@alg_name: Name of algorithm
415  *	@type: Type of algorithm
416  *	@mask: Mask for type comparison
417  *
418  *	This function should not be used by new algorithm types.
419  *	Plesae use crypto_alloc_tfm instead.
420  *
421  *	crypto_alloc_base() will first attempt to locate an already loaded
422  *	algorithm.  If that fails and the kernel supports dynamically loadable
423  *	modules, it will then attempt to load a module of the same name or
424  *	alias.  If that fails it will send a query to any loaded crypto manager
425  *	to construct an algorithm on the fly.  A refcount is grabbed on the
426  *	algorithm which is then associated with the new transform.
427  *
428  *	The returned transform is of a non-determinate type.  Most people
429  *	should use one of the more specific allocation functions such as
430  *	crypto_alloc_blkcipher.
431  *
432  *	In case of error the return value is an error pointer.
433  */
434 struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
435 {
436 	struct crypto_tfm *tfm;
437 	int err;
438 
439 	for (;;) {
440 		struct crypto_alg *alg;
441 
442 		alg = crypto_alg_mod_lookup(alg_name, type, mask);
443 		if (IS_ERR(alg)) {
444 			err = PTR_ERR(alg);
445 			goto err;
446 		}
447 
448 		tfm = __crypto_alloc_tfm(alg, type, mask);
449 		if (!IS_ERR(tfm))
450 			return tfm;
451 
452 		crypto_mod_put(alg);
453 		err = PTR_ERR(tfm);
454 
455 err:
456 		if (err != -EAGAIN)
457 			break;
458 		if (signal_pending(current)) {
459 			err = -EINTR;
460 			break;
461 		}
462 	}
463 
464 	return ERR_PTR(err);
465 }
466 EXPORT_SYMBOL_GPL(crypto_alloc_base);
467 
468 void *crypto_create_tfm(struct crypto_alg *alg,
469 			const struct crypto_type *frontend)
470 {
471 	char *mem;
472 	struct crypto_tfm *tfm = NULL;
473 	unsigned int tfmsize;
474 	unsigned int total;
475 	int err = -ENOMEM;
476 
477 	tfmsize = frontend->tfmsize;
478 	total = tfmsize + sizeof(*tfm) + frontend->extsize(alg, frontend);
479 
480 	mem = kzalloc(total, GFP_KERNEL);
481 	if (mem == NULL)
482 		goto out_err;
483 
484 	tfm = (struct crypto_tfm *)(mem + tfmsize);
485 	tfm->__crt_alg = alg;
486 
487 	err = frontend->init_tfm(tfm, frontend);
488 	if (err)
489 		goto out_free_tfm;
490 
491 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
492 		goto cra_init_failed;
493 
494 	goto out;
495 
496 cra_init_failed:
497 	crypto_exit_ops(tfm);
498 out_free_tfm:
499 	if (err == -EAGAIN)
500 		crypto_shoot_alg(alg);
501 	kfree(mem);
502 out_err:
503 	mem = ERR_PTR(err);
504 out:
505 	return mem;
506 }
507 EXPORT_SYMBOL_GPL(crypto_create_tfm);
508 
509 /*
510  *	crypto_alloc_tfm - Locate algorithm and allocate transform
511  *	@alg_name: Name of algorithm
512  *	@frontend: Frontend algorithm type
513  *	@type: Type of algorithm
514  *	@mask: Mask for type comparison
515  *
516  *	crypto_alloc_tfm() will first attempt to locate an already loaded
517  *	algorithm.  If that fails and the kernel supports dynamically loadable
518  *	modules, it will then attempt to load a module of the same name or
519  *	alias.  If that fails it will send a query to any loaded crypto manager
520  *	to construct an algorithm on the fly.  A refcount is grabbed on the
521  *	algorithm which is then associated with the new transform.
522  *
523  *	The returned transform is of a non-determinate type.  Most people
524  *	should use one of the more specific allocation functions such as
525  *	crypto_alloc_blkcipher.
526  *
527  *	In case of error the return value is an error pointer.
528  */
529 void *crypto_alloc_tfm(const char *alg_name,
530 		       const struct crypto_type *frontend, u32 type, u32 mask)
531 {
532 	struct crypto_alg *(*lookup)(const char *name, u32 type, u32 mask);
533 	void *tfm;
534 	int err;
535 
536 	type &= frontend->maskclear;
537 	mask &= frontend->maskclear;
538 	type |= frontend->type;
539 	mask |= frontend->maskset;
540 
541 	lookup = frontend->lookup ?: crypto_alg_mod_lookup;
542 
543 	for (;;) {
544 		struct crypto_alg *alg;
545 
546 		alg = lookup(alg_name, type, mask);
547 		if (IS_ERR(alg)) {
548 			err = PTR_ERR(alg);
549 			goto err;
550 		}
551 
552 		tfm = crypto_create_tfm(alg, frontend);
553 		if (!IS_ERR(tfm))
554 			return tfm;
555 
556 		crypto_mod_put(alg);
557 		err = PTR_ERR(tfm);
558 
559 err:
560 		if (err != -EAGAIN)
561 			break;
562 		if (signal_pending(current)) {
563 			err = -EINTR;
564 			break;
565 		}
566 	}
567 
568 	return ERR_PTR(err);
569 }
570 EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
571 
572 /*
573  *	crypto_destroy_tfm - Free crypto transform
574  *	@mem: Start of tfm slab
575  *	@tfm: Transform to free
576  *
577  *	This function frees up the transform and any associated resources,
578  *	then drops the refcount on the associated algorithm.
579  */
580 void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
581 {
582 	struct crypto_alg *alg;
583 	int size;
584 
585 	if (unlikely(!mem))
586 		return;
587 
588 	alg = tfm->__crt_alg;
589 	size = ksize(mem);
590 
591 	if (!tfm->exit && alg->cra_exit)
592 		alg->cra_exit(tfm);
593 	crypto_exit_ops(tfm);
594 	crypto_mod_put(alg);
595 	memset(mem, 0, size);
596 	kfree(mem);
597 }
598 EXPORT_SYMBOL_GPL(crypto_destroy_tfm);
599 
600 int crypto_has_alg(const char *name, u32 type, u32 mask)
601 {
602 	int ret = 0;
603 	struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
604 
605 	if (!IS_ERR(alg)) {
606 		crypto_mod_put(alg);
607 		ret = 1;
608 	}
609 
610 	return ret;
611 }
612 EXPORT_SYMBOL_GPL(crypto_has_alg);
613 
614 MODULE_DESCRIPTION("Cryptographic core API");
615 MODULE_LICENSE("GPL");
616