xref: /openbmc/linux/crypto/api.c (revision b04b4f78) 
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 		    snprintf(tmp, sizeof(tmp), "%s-all", name) < sizeof(tmp))
226 			request_module(tmp);
227 
228 		alg = crypto_alg_lookup(name, type, mask);
229 	}
230 
231 	if (alg)
232 		return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
233 
234 	return crypto_larval_add(name, type, mask);
235 }
236 EXPORT_SYMBOL_GPL(crypto_larval_lookup);
237 
238 int crypto_probing_notify(unsigned long val, void *v)
239 {
240 	int ok;
241 
242 	ok = blocking_notifier_call_chain(&crypto_chain, val, v);
243 	if (ok == NOTIFY_DONE) {
244 		request_module("cryptomgr");
245 		ok = blocking_notifier_call_chain(&crypto_chain, val, v);
246 	}
247 
248 	return ok;
249 }
250 EXPORT_SYMBOL_GPL(crypto_probing_notify);
251 
252 struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
253 {
254 	struct crypto_alg *alg;
255 	struct crypto_alg *larval;
256 	int ok;
257 
258 	if (!((type | mask) & CRYPTO_ALG_TESTED)) {
259 		type |= CRYPTO_ALG_TESTED;
260 		mask |= CRYPTO_ALG_TESTED;
261 	}
262 
263 	larval = crypto_larval_lookup(name, type, mask);
264 	if (IS_ERR(larval) || !crypto_is_larval(larval))
265 		return larval;
266 
267 	ok = crypto_probing_notify(CRYPTO_MSG_ALG_REQUEST, larval);
268 
269 	if (ok == NOTIFY_STOP)
270 		alg = crypto_larval_wait(larval);
271 	else {
272 		crypto_mod_put(larval);
273 		alg = ERR_PTR(-ENOENT);
274 	}
275 	crypto_larval_kill(larval);
276 	return alg;
277 }
278 EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
279 
280 static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
281 {
282 	const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
283 
284 	if (type_obj)
285 		return type_obj->init(tfm, type, mask);
286 
287 	switch (crypto_tfm_alg_type(tfm)) {
288 	case CRYPTO_ALG_TYPE_CIPHER:
289 		return crypto_init_cipher_ops(tfm);
290 
291 	case CRYPTO_ALG_TYPE_DIGEST:
292 		if ((mask & CRYPTO_ALG_TYPE_HASH_MASK) !=
293 		    CRYPTO_ALG_TYPE_HASH_MASK)
294 			return crypto_init_digest_ops_async(tfm);
295 		else
296 			return crypto_init_digest_ops(tfm);
297 
298 	case CRYPTO_ALG_TYPE_COMPRESS:
299 		return crypto_init_compress_ops(tfm);
300 
301 	default:
302 		break;
303 	}
304 
305 	BUG();
306 	return -EINVAL;
307 }
308 
309 static void crypto_exit_ops(struct crypto_tfm *tfm)
310 {
311 	const struct crypto_type *type = tfm->__crt_alg->cra_type;
312 
313 	if (type) {
314 		if (tfm->exit)
315 			tfm->exit(tfm);
316 		return;
317 	}
318 
319 	switch (crypto_tfm_alg_type(tfm)) {
320 	case CRYPTO_ALG_TYPE_CIPHER:
321 		crypto_exit_cipher_ops(tfm);
322 		break;
323 
324 	case CRYPTO_ALG_TYPE_DIGEST:
325 		crypto_exit_digest_ops(tfm);
326 		break;
327 
328 	case CRYPTO_ALG_TYPE_COMPRESS:
329 		crypto_exit_compress_ops(tfm);
330 		break;
331 
332 	default:
333 		BUG();
334 
335 	}
336 }
337 
338 static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
339 {
340 	const struct crypto_type *type_obj = alg->cra_type;
341 	unsigned int len;
342 
343 	len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
344 	if (type_obj)
345 		return len + type_obj->ctxsize(alg, type, mask);
346 
347 	switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
348 	default:
349 		BUG();
350 
351 	case CRYPTO_ALG_TYPE_CIPHER:
352 		len += crypto_cipher_ctxsize(alg);
353 		break;
354 
355 	case CRYPTO_ALG_TYPE_DIGEST:
356 		len += crypto_digest_ctxsize(alg);
357 		break;
358 
359 	case CRYPTO_ALG_TYPE_COMPRESS:
360 		len += crypto_compress_ctxsize(alg);
361 		break;
362 	}
363 
364 	return len;
365 }
366 
367 void crypto_shoot_alg(struct crypto_alg *alg)
368 {
369 	down_write(&crypto_alg_sem);
370 	alg->cra_flags |= CRYPTO_ALG_DYING;
371 	up_write(&crypto_alg_sem);
372 }
373 EXPORT_SYMBOL_GPL(crypto_shoot_alg);
374 
375 struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
376 				      u32 mask)
377 {
378 	struct crypto_tfm *tfm = NULL;
379 	unsigned int tfm_size;
380 	int err = -ENOMEM;
381 
382 	tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
383 	tfm = kzalloc(tfm_size, GFP_KERNEL);
384 	if (tfm == NULL)
385 		goto out_err;
386 
387 	tfm->__crt_alg = alg;
388 
389 	err = crypto_init_ops(tfm, type, mask);
390 	if (err)
391 		goto out_free_tfm;
392 
393 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
394 		goto cra_init_failed;
395 
396 	goto out;
397 
398 cra_init_failed:
399 	crypto_exit_ops(tfm);
400 out_free_tfm:
401 	if (err == -EAGAIN)
402 		crypto_shoot_alg(alg);
403 	kfree(tfm);
404 out_err:
405 	tfm = ERR_PTR(err);
406 out:
407 	return tfm;
408 }
409 EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
410 
411 /*
412  *	crypto_alloc_base - Locate algorithm and allocate transform
413  *	@alg_name: Name of algorithm
414  *	@type: Type of algorithm
415  *	@mask: Mask for type comparison
416  *
417  *	This function should not be used by new algorithm types.
418  *	Plesae use crypto_alloc_tfm instead.
419  *
420  *	crypto_alloc_base() will first attempt to locate an already loaded
421  *	algorithm.  If that fails and the kernel supports dynamically loadable
422  *	modules, it will then attempt to load a module of the same name or
423  *	alias.  If that fails it will send a query to any loaded crypto manager
424  *	to construct an algorithm on the fly.  A refcount is grabbed on the
425  *	algorithm which is then associated with the new transform.
426  *
427  *	The returned transform is of a non-determinate type.  Most people
428  *	should use one of the more specific allocation functions such as
429  *	crypto_alloc_blkcipher.
430  *
431  *	In case of error the return value is an error pointer.
432  */
433 struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
434 {
435 	struct crypto_tfm *tfm;
436 	int err;
437 
438 	for (;;) {
439 		struct crypto_alg *alg;
440 
441 		alg = crypto_alg_mod_lookup(alg_name, type, mask);
442 		if (IS_ERR(alg)) {
443 			err = PTR_ERR(alg);
444 			goto err;
445 		}
446 
447 		tfm = __crypto_alloc_tfm(alg, type, mask);
448 		if (!IS_ERR(tfm))
449 			return tfm;
450 
451 		crypto_mod_put(alg);
452 		err = PTR_ERR(tfm);
453 
454 err:
455 		if (err != -EAGAIN)
456 			break;
457 		if (signal_pending(current)) {
458 			err = -EINTR;
459 			break;
460 		}
461 	}
462 
463 	return ERR_PTR(err);
464 }
465 EXPORT_SYMBOL_GPL(crypto_alloc_base);
466 
467 void *crypto_create_tfm(struct crypto_alg *alg,
468 			const struct crypto_type *frontend)
469 {
470 	char *mem;
471 	struct crypto_tfm *tfm = NULL;
472 	unsigned int tfmsize;
473 	unsigned int total;
474 	int err = -ENOMEM;
475 
476 	tfmsize = frontend->tfmsize;
477 	total = tfmsize + sizeof(*tfm) + frontend->extsize(alg, frontend);
478 
479 	mem = kzalloc(total, GFP_KERNEL);
480 	if (mem == NULL)
481 		goto out_err;
482 
483 	tfm = (struct crypto_tfm *)(mem + tfmsize);
484 	tfm->__crt_alg = alg;
485 
486 	err = frontend->init_tfm(tfm, frontend);
487 	if (err)
488 		goto out_free_tfm;
489 
490 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
491 		goto cra_init_failed;
492 
493 	goto out;
494 
495 cra_init_failed:
496 	crypto_exit_ops(tfm);
497 out_free_tfm:
498 	if (err == -EAGAIN)
499 		crypto_shoot_alg(alg);
500 	kfree(mem);
501 out_err:
502 	mem = ERR_PTR(err);
503 out:
504 	return mem;
505 }
506 EXPORT_SYMBOL_GPL(crypto_create_tfm);
507 
508 /*
509  *	crypto_alloc_tfm - Locate algorithm and allocate transform
510  *	@alg_name: Name of algorithm
511  *	@frontend: Frontend algorithm type
512  *	@type: Type of algorithm
513  *	@mask: Mask for type comparison
514  *
515  *	crypto_alloc_tfm() will first attempt to locate an already loaded
516  *	algorithm.  If that fails and the kernel supports dynamically loadable
517  *	modules, it will then attempt to load a module of the same name or
518  *	alias.  If that fails it will send a query to any loaded crypto manager
519  *	to construct an algorithm on the fly.  A refcount is grabbed on the
520  *	algorithm which is then associated with the new transform.
521  *
522  *	The returned transform is of a non-determinate type.  Most people
523  *	should use one of the more specific allocation functions such as
524  *	crypto_alloc_blkcipher.
525  *
526  *	In case of error the return value is an error pointer.
527  */
528 void *crypto_alloc_tfm(const char *alg_name,
529 		       const struct crypto_type *frontend, u32 type, u32 mask)
530 {
531 	struct crypto_alg *(*lookup)(const char *name, u32 type, u32 mask);
532 	void *tfm;
533 	int err;
534 
535 	type &= frontend->maskclear;
536 	mask &= frontend->maskclear;
537 	type |= frontend->type;
538 	mask |= frontend->maskset;
539 
540 	lookup = frontend->lookup ?: crypto_alg_mod_lookup;
541 
542 	for (;;) {
543 		struct crypto_alg *alg;
544 
545 		alg = lookup(alg_name, type, mask);
546 		if (IS_ERR(alg)) {
547 			err = PTR_ERR(alg);
548 			goto err;
549 		}
550 
551 		tfm = crypto_create_tfm(alg, frontend);
552 		if (!IS_ERR(tfm))
553 			return tfm;
554 
555 		crypto_mod_put(alg);
556 		err = PTR_ERR(tfm);
557 
558 err:
559 		if (err != -EAGAIN)
560 			break;
561 		if (signal_pending(current)) {
562 			err = -EINTR;
563 			break;
564 		}
565 	}
566 
567 	return ERR_PTR(err);
568 }
569 EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
570 
571 /*
572  *	crypto_destroy_tfm - Free crypto transform
573  *	@mem: Start of tfm slab
574  *	@tfm: Transform to free
575  *
576  *	This function frees up the transform and any associated resources,
577  *	then drops the refcount on the associated algorithm.
578  */
579 void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
580 {
581 	struct crypto_alg *alg;
582 	int size;
583 
584 	if (unlikely(!mem))
585 		return;
586 
587 	alg = tfm->__crt_alg;
588 	size = ksize(mem);
589 
590 	if (!tfm->exit && alg->cra_exit)
591 		alg->cra_exit(tfm);
592 	crypto_exit_ops(tfm);
593 	crypto_mod_put(alg);
594 	memset(mem, 0, size);
595 	kfree(mem);
596 }
597 EXPORT_SYMBOL_GPL(crypto_destroy_tfm);
598 
599 int crypto_has_alg(const char *name, u32 type, u32 mask)
600 {
601 	int ret = 0;
602 	struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
603 
604 	if (!IS_ERR(alg)) {
605 		crypto_mod_put(alg);
606 		ret = 1;
607 	}
608 
609 	return ret;
610 }
611 EXPORT_SYMBOL_GPL(crypto_has_alg);
612 
613 MODULE_DESCRIPTION("Cryptographic core API");
614 MODULE_LICENSE("GPL");
615