xref: /linux/crypto/api.c (revision 5bdef865eb358b6f3760e25e591ae115e9eeddef) 
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 		request_module("%s", name);
221 
222 		if (!((type ^ CRYPTO_ALG_NEED_FALLBACK) & mask &
223 		      CRYPTO_ALG_NEED_FALLBACK))
224 			request_module("%s-all", name);
225 
226 		alg = crypto_alg_lookup(name, type, mask);
227 	}
228 
229 	if (alg)
230 		return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
231 
232 	return crypto_larval_add(name, type, mask);
233 }
234 EXPORT_SYMBOL_GPL(crypto_larval_lookup);
235 
236 int crypto_probing_notify(unsigned long val, void *v)
237 {
238 	int ok;
239 
240 	ok = blocking_notifier_call_chain(&crypto_chain, val, v);
241 	if (ok == NOTIFY_DONE) {
242 		request_module("cryptomgr");
243 		ok = blocking_notifier_call_chain(&crypto_chain, val, v);
244 	}
245 
246 	return ok;
247 }
248 EXPORT_SYMBOL_GPL(crypto_probing_notify);
249 
250 struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
251 {
252 	struct crypto_alg *alg;
253 	struct crypto_alg *larval;
254 	int ok;
255 
256 	if (!((type | mask) & CRYPTO_ALG_TESTED)) {
257 		type |= CRYPTO_ALG_TESTED;
258 		mask |= CRYPTO_ALG_TESTED;
259 	}
260 
261 	larval = crypto_larval_lookup(name, type, mask);
262 	if (IS_ERR(larval) || !crypto_is_larval(larval))
263 		return larval;
264 
265 	ok = crypto_probing_notify(CRYPTO_MSG_ALG_REQUEST, larval);
266 
267 	if (ok == NOTIFY_STOP)
268 		alg = crypto_larval_wait(larval);
269 	else {
270 		crypto_mod_put(larval);
271 		alg = ERR_PTR(-ENOENT);
272 	}
273 	crypto_larval_kill(larval);
274 	return alg;
275 }
276 EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
277 
278 static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
279 {
280 	const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
281 
282 	if (type_obj)
283 		return type_obj->init(tfm, type, mask);
284 
285 	switch (crypto_tfm_alg_type(tfm)) {
286 	case CRYPTO_ALG_TYPE_CIPHER:
287 		return crypto_init_cipher_ops(tfm);
288 
289 	case CRYPTO_ALG_TYPE_DIGEST:
290 		if ((mask & CRYPTO_ALG_TYPE_HASH_MASK) !=
291 		    CRYPTO_ALG_TYPE_HASH_MASK)
292 			return crypto_init_digest_ops_async(tfm);
293 		else
294 			return crypto_init_digest_ops(tfm);
295 
296 	case CRYPTO_ALG_TYPE_COMPRESS:
297 		return crypto_init_compress_ops(tfm);
298 
299 	default:
300 		break;
301 	}
302 
303 	BUG();
304 	return -EINVAL;
305 }
306 
307 static void crypto_exit_ops(struct crypto_tfm *tfm)
308 {
309 	const struct crypto_type *type = tfm->__crt_alg->cra_type;
310 
311 	if (type) {
312 		if (tfm->exit)
313 			tfm->exit(tfm);
314 		return;
315 	}
316 
317 	switch (crypto_tfm_alg_type(tfm)) {
318 	case CRYPTO_ALG_TYPE_CIPHER:
319 		crypto_exit_cipher_ops(tfm);
320 		break;
321 
322 	case CRYPTO_ALG_TYPE_DIGEST:
323 		crypto_exit_digest_ops(tfm);
324 		break;
325 
326 	case CRYPTO_ALG_TYPE_COMPRESS:
327 		crypto_exit_compress_ops(tfm);
328 		break;
329 
330 	default:
331 		BUG();
332 
333 	}
334 }
335 
336 static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
337 {
338 	const struct crypto_type *type_obj = alg->cra_type;
339 	unsigned int len;
340 
341 	len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
342 	if (type_obj)
343 		return len + type_obj->ctxsize(alg, type, mask);
344 
345 	switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
346 	default:
347 		BUG();
348 
349 	case CRYPTO_ALG_TYPE_CIPHER:
350 		len += crypto_cipher_ctxsize(alg);
351 		break;
352 
353 	case CRYPTO_ALG_TYPE_DIGEST:
354 		len += crypto_digest_ctxsize(alg);
355 		break;
356 
357 	case CRYPTO_ALG_TYPE_COMPRESS:
358 		len += crypto_compress_ctxsize(alg);
359 		break;
360 	}
361 
362 	return len;
363 }
364 
365 void crypto_shoot_alg(struct crypto_alg *alg)
366 {
367 	down_write(&crypto_alg_sem);
368 	alg->cra_flags |= CRYPTO_ALG_DYING;
369 	up_write(&crypto_alg_sem);
370 }
371 EXPORT_SYMBOL_GPL(crypto_shoot_alg);
372 
373 struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
374 				      u32 mask)
375 {
376 	struct crypto_tfm *tfm = NULL;
377 	unsigned int tfm_size;
378 	int err = -ENOMEM;
379 
380 	tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
381 	tfm = kzalloc(tfm_size, GFP_KERNEL);
382 	if (tfm == NULL)
383 		goto out_err;
384 
385 	tfm->__crt_alg = alg;
386 
387 	err = crypto_init_ops(tfm, type, mask);
388 	if (err)
389 		goto out_free_tfm;
390 
391 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
392 		goto cra_init_failed;
393 
394 	goto out;
395 
396 cra_init_failed:
397 	crypto_exit_ops(tfm);
398 out_free_tfm:
399 	if (err == -EAGAIN)
400 		crypto_shoot_alg(alg);
401 	kfree(tfm);
402 out_err:
403 	tfm = ERR_PTR(err);
404 out:
405 	return tfm;
406 }
407 EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
408 
409 /*
410  *	crypto_alloc_base - Locate algorithm and allocate transform
411  *	@alg_name: Name of algorithm
412  *	@type: Type of algorithm
413  *	@mask: Mask for type comparison
414  *
415  *	This function should not be used by new algorithm types.
416  *	Plesae use crypto_alloc_tfm instead.
417  *
418  *	crypto_alloc_base() will first attempt to locate an already loaded
419  *	algorithm.  If that fails and the kernel supports dynamically loadable
420  *	modules, it will then attempt to load a module of the same name or
421  *	alias.  If that fails it will send a query to any loaded crypto manager
422  *	to construct an algorithm on the fly.  A refcount is grabbed on the
423  *	algorithm which is then associated with the new transform.
424  *
425  *	The returned transform is of a non-determinate type.  Most people
426  *	should use one of the more specific allocation functions such as
427  *	crypto_alloc_blkcipher.
428  *
429  *	In case of error the return value is an error pointer.
430  */
431 struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
432 {
433 	struct crypto_tfm *tfm;
434 	int err;
435 
436 	for (;;) {
437 		struct crypto_alg *alg;
438 
439 		alg = crypto_alg_mod_lookup(alg_name, type, mask);
440 		if (IS_ERR(alg)) {
441 			err = PTR_ERR(alg);
442 			goto err;
443 		}
444 
445 		tfm = __crypto_alloc_tfm(alg, type, mask);
446 		if (!IS_ERR(tfm))
447 			return tfm;
448 
449 		crypto_mod_put(alg);
450 		err = PTR_ERR(tfm);
451 
452 err:
453 		if (err != -EAGAIN)
454 			break;
455 		if (signal_pending(current)) {
456 			err = -EINTR;
457 			break;
458 		}
459 	}
460 
461 	return ERR_PTR(err);
462 }
463 EXPORT_SYMBOL_GPL(crypto_alloc_base);
464 
465 void *crypto_create_tfm(struct crypto_alg *alg,
466 			const struct crypto_type *frontend)
467 {
468 	char *mem;
469 	struct crypto_tfm *tfm = NULL;
470 	unsigned int tfmsize;
471 	unsigned int total;
472 	int err = -ENOMEM;
473 
474 	tfmsize = frontend->tfmsize;
475 	total = tfmsize + sizeof(*tfm) + frontend->extsize(alg, frontend);
476 
477 	mem = kzalloc(total, GFP_KERNEL);
478 	if (mem == NULL)
479 		goto out_err;
480 
481 	tfm = (struct crypto_tfm *)(mem + tfmsize);
482 	tfm->__crt_alg = alg;
483 
484 	err = frontend->init_tfm(tfm, frontend);
485 	if (err)
486 		goto out_free_tfm;
487 
488 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
489 		goto cra_init_failed;
490 
491 	goto out;
492 
493 cra_init_failed:
494 	crypto_exit_ops(tfm);
495 out_free_tfm:
496 	if (err == -EAGAIN)
497 		crypto_shoot_alg(alg);
498 	kfree(mem);
499 out_err:
500 	mem = ERR_PTR(err);
501 out:
502 	return mem;
503 }
504 EXPORT_SYMBOL_GPL(crypto_create_tfm);
505 
506 /*
507  *	crypto_alloc_tfm - Locate algorithm and allocate transform
508  *	@alg_name: Name of algorithm
509  *	@frontend: Frontend algorithm type
510  *	@type: Type of algorithm
511  *	@mask: Mask for type comparison
512  *
513  *	crypto_alloc_tfm() will first attempt to locate an already loaded
514  *	algorithm.  If that fails and the kernel supports dynamically loadable
515  *	modules, it will then attempt to load a module of the same name or
516  *	alias.  If that fails it will send a query to any loaded crypto manager
517  *	to construct an algorithm on the fly.  A refcount is grabbed on the
518  *	algorithm which is then associated with the new transform.
519  *
520  *	The returned transform is of a non-determinate type.  Most people
521  *	should use one of the more specific allocation functions such as
522  *	crypto_alloc_blkcipher.
523  *
524  *	In case of error the return value is an error pointer.
525  */
526 void *crypto_alloc_tfm(const char *alg_name,
527 		       const struct crypto_type *frontend, u32 type, u32 mask)
528 {
529 	struct crypto_alg *(*lookup)(const char *name, u32 type, u32 mask);
530 	void *tfm;
531 	int err;
532 
533 	type &= frontend->maskclear;
534 	mask &= frontend->maskclear;
535 	type |= frontend->type;
536 	mask |= frontend->maskset;
537 
538 	lookup = frontend->lookup ?: crypto_alg_mod_lookup;
539 
540 	for (;;) {
541 		struct crypto_alg *alg;
542 
543 		alg = lookup(alg_name, type, mask);
544 		if (IS_ERR(alg)) {
545 			err = PTR_ERR(alg);
546 			goto err;
547 		}
548 
549 		tfm = crypto_create_tfm(alg, frontend);
550 		if (!IS_ERR(tfm))
551 			return tfm;
552 
553 		crypto_mod_put(alg);
554 		err = PTR_ERR(tfm);
555 
556 err:
557 		if (err != -EAGAIN)
558 			break;
559 		if (signal_pending(current)) {
560 			err = -EINTR;
561 			break;
562 		}
563 	}
564 
565 	return ERR_PTR(err);
566 }
567 EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
568 
569 /*
570  *	crypto_destroy_tfm - Free crypto transform
571  *	@mem: Start of tfm slab
572  *	@tfm: Transform to free
573  *
574  *	This function frees up the transform and any associated resources,
575  *	then drops the refcount on the associated algorithm.
576  */
577 void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
578 {
579 	struct crypto_alg *alg;
580 
581 	if (unlikely(!mem))
582 		return;
583 
584 	alg = tfm->__crt_alg;
585 
586 	if (!tfm->exit && alg->cra_exit)
587 		alg->cra_exit(tfm);
588 	crypto_exit_ops(tfm);
589 	crypto_mod_put(alg);
590 	kzfree(mem);
591 }
592 EXPORT_SYMBOL_GPL(crypto_destroy_tfm);
593 
594 int crypto_has_alg(const char *name, u32 type, u32 mask)
595 {
596 	int ret = 0;
597 	struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
598 
599 	if (!IS_ERR(alg)) {
600 		crypto_mod_put(alg);
601 		ret = 1;
602 	}
603 
604 	return ret;
605 }
606 EXPORT_SYMBOL_GPL(crypto_has_alg);
607 
608 MODULE_DESCRIPTION("Cryptographic core API");
609 MODULE_LICENSE("GPL");
610