xref: /linux/crypto/api.c (revision b233b28eac0cc37d07c2d007ea08c86c778c5af4) 
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 = try_then_request_module(crypto_alg_lookup(name, type, mask),
219 				      name);
220 	if (alg)
221 		return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
222 
223 	return crypto_larval_add(name, type, mask);
224 }
225 EXPORT_SYMBOL_GPL(crypto_larval_lookup);
226 
227 int crypto_probing_notify(unsigned long val, void *v)
228 {
229 	int ok;
230 
231 	ok = blocking_notifier_call_chain(&crypto_chain, val, v);
232 	if (ok == NOTIFY_DONE) {
233 		request_module("cryptomgr");
234 		ok = blocking_notifier_call_chain(&crypto_chain, val, v);
235 	}
236 
237 	return ok;
238 }
239 EXPORT_SYMBOL_GPL(crypto_probing_notify);
240 
241 struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
242 {
243 	struct crypto_alg *alg;
244 	struct crypto_alg *larval;
245 	int ok;
246 
247 	if (!(mask & CRYPTO_ALG_TESTED)) {
248 		type |= CRYPTO_ALG_TESTED;
249 		mask |= CRYPTO_ALG_TESTED;
250 	}
251 
252 	larval = crypto_larval_lookup(name, type, mask);
253 	if (IS_ERR(larval) || !crypto_is_larval(larval))
254 		return larval;
255 
256 	ok = crypto_probing_notify(CRYPTO_MSG_ALG_REQUEST, larval);
257 
258 	if (ok == NOTIFY_STOP)
259 		alg = crypto_larval_wait(larval);
260 	else {
261 		crypto_mod_put(larval);
262 		alg = ERR_PTR(-ENOENT);
263 	}
264 	crypto_larval_kill(larval);
265 	return alg;
266 }
267 EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
268 
269 static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
270 {
271 	const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
272 
273 	if (type_obj)
274 		return type_obj->init(tfm, type, mask);
275 
276 	switch (crypto_tfm_alg_type(tfm)) {
277 	case CRYPTO_ALG_TYPE_CIPHER:
278 		return crypto_init_cipher_ops(tfm);
279 
280 	case CRYPTO_ALG_TYPE_DIGEST:
281 		if ((mask & CRYPTO_ALG_TYPE_HASH_MASK) !=
282 		    CRYPTO_ALG_TYPE_HASH_MASK)
283 			return crypto_init_digest_ops_async(tfm);
284 		else
285 			return crypto_init_digest_ops(tfm);
286 
287 	case CRYPTO_ALG_TYPE_COMPRESS:
288 		return crypto_init_compress_ops(tfm);
289 
290 	default:
291 		break;
292 	}
293 
294 	BUG();
295 	return -EINVAL;
296 }
297 
298 static void crypto_exit_ops(struct crypto_tfm *tfm)
299 {
300 	const struct crypto_type *type = tfm->__crt_alg->cra_type;
301 
302 	if (type) {
303 		if (tfm->exit)
304 			tfm->exit(tfm);
305 		return;
306 	}
307 
308 	switch (crypto_tfm_alg_type(tfm)) {
309 	case CRYPTO_ALG_TYPE_CIPHER:
310 		crypto_exit_cipher_ops(tfm);
311 		break;
312 
313 	case CRYPTO_ALG_TYPE_DIGEST:
314 		crypto_exit_digest_ops(tfm);
315 		break;
316 
317 	case CRYPTO_ALG_TYPE_COMPRESS:
318 		crypto_exit_compress_ops(tfm);
319 		break;
320 
321 	default:
322 		BUG();
323 
324 	}
325 }
326 
327 static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
328 {
329 	const struct crypto_type *type_obj = alg->cra_type;
330 	unsigned int len;
331 
332 	len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
333 	if (type_obj)
334 		return len + type_obj->ctxsize(alg, type, mask);
335 
336 	switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
337 	default:
338 		BUG();
339 
340 	case CRYPTO_ALG_TYPE_CIPHER:
341 		len += crypto_cipher_ctxsize(alg);
342 		break;
343 
344 	case CRYPTO_ALG_TYPE_DIGEST:
345 		len += crypto_digest_ctxsize(alg);
346 		break;
347 
348 	case CRYPTO_ALG_TYPE_COMPRESS:
349 		len += crypto_compress_ctxsize(alg);
350 		break;
351 	}
352 
353 	return len;
354 }
355 
356 void crypto_shoot_alg(struct crypto_alg *alg)
357 {
358 	down_write(&crypto_alg_sem);
359 	alg->cra_flags |= CRYPTO_ALG_DYING;
360 	up_write(&crypto_alg_sem);
361 }
362 EXPORT_SYMBOL_GPL(crypto_shoot_alg);
363 
364 struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
365 				      u32 mask)
366 {
367 	struct crypto_tfm *tfm = NULL;
368 	unsigned int tfm_size;
369 	int err = -ENOMEM;
370 
371 	tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
372 	tfm = kzalloc(tfm_size, GFP_KERNEL);
373 	if (tfm == NULL)
374 		goto out_err;
375 
376 	tfm->__crt_alg = alg;
377 
378 	err = crypto_init_ops(tfm, type, mask);
379 	if (err)
380 		goto out_free_tfm;
381 
382 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
383 		goto cra_init_failed;
384 
385 	goto out;
386 
387 cra_init_failed:
388 	crypto_exit_ops(tfm);
389 out_free_tfm:
390 	if (err == -EAGAIN)
391 		crypto_shoot_alg(alg);
392 	kfree(tfm);
393 out_err:
394 	tfm = ERR_PTR(err);
395 out:
396 	return tfm;
397 }
398 EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
399 
400 /*
401  *	crypto_alloc_base - Locate algorithm and allocate transform
402  *	@alg_name: Name of algorithm
403  *	@type: Type of algorithm
404  *	@mask: Mask for type comparison
405  *
406  *	This function should not be used by new algorithm types.
407  *	Plesae use crypto_alloc_tfm instead.
408  *
409  *	crypto_alloc_base() will first attempt to locate an already loaded
410  *	algorithm.  If that fails and the kernel supports dynamically loadable
411  *	modules, it will then attempt to load a module of the same name or
412  *	alias.  If that fails it will send a query to any loaded crypto manager
413  *	to construct an algorithm on the fly.  A refcount is grabbed on the
414  *	algorithm which is then associated with the new transform.
415  *
416  *	The returned transform is of a non-determinate type.  Most people
417  *	should use one of the more specific allocation functions such as
418  *	crypto_alloc_blkcipher.
419  *
420  *	In case of error the return value is an error pointer.
421  */
422 struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
423 {
424 	struct crypto_tfm *tfm;
425 	int err;
426 
427 	for (;;) {
428 		struct crypto_alg *alg;
429 
430 		alg = crypto_alg_mod_lookup(alg_name, type, mask);
431 		if (IS_ERR(alg)) {
432 			err = PTR_ERR(alg);
433 			goto err;
434 		}
435 
436 		tfm = __crypto_alloc_tfm(alg, type, mask);
437 		if (!IS_ERR(tfm))
438 			return tfm;
439 
440 		crypto_mod_put(alg);
441 		err = PTR_ERR(tfm);
442 
443 err:
444 		if (err != -EAGAIN)
445 			break;
446 		if (signal_pending(current)) {
447 			err = -EINTR;
448 			break;
449 		}
450 	}
451 
452 	return ERR_PTR(err);
453 }
454 EXPORT_SYMBOL_GPL(crypto_alloc_base);
455 
456 struct crypto_tfm *crypto_create_tfm(struct crypto_alg *alg,
457 				     const struct crypto_type *frontend)
458 {
459 	char *mem;
460 	struct crypto_tfm *tfm = NULL;
461 	unsigned int tfmsize;
462 	unsigned int total;
463 	int err = -ENOMEM;
464 
465 	tfmsize = frontend->tfmsize;
466 	total = tfmsize + sizeof(*tfm) + frontend->extsize(alg, frontend);
467 
468 	mem = kzalloc(total, GFP_KERNEL);
469 	if (mem == NULL)
470 		goto out_err;
471 
472 	tfm = (struct crypto_tfm *)(mem + tfmsize);
473 	tfm->__crt_alg = alg;
474 
475 	err = frontend->init_tfm(tfm, frontend);
476 	if (err)
477 		goto out_free_tfm;
478 
479 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
480 		goto cra_init_failed;
481 
482 	goto out;
483 
484 cra_init_failed:
485 	crypto_exit_ops(tfm);
486 out_free_tfm:
487 	if (err == -EAGAIN)
488 		crypto_shoot_alg(alg);
489 	kfree(mem);
490 out_err:
491 	tfm = ERR_PTR(err);
492 out:
493 	return tfm;
494 }
495 EXPORT_SYMBOL_GPL(crypto_create_tfm);
496 
497 /*
498  *	crypto_alloc_tfm - Locate algorithm and allocate transform
499  *	@alg_name: Name of algorithm
500  *	@frontend: Frontend algorithm type
501  *	@type: Type of algorithm
502  *	@mask: Mask for type comparison
503  *
504  *	crypto_alloc_tfm() will first attempt to locate an already loaded
505  *	algorithm.  If that fails and the kernel supports dynamically loadable
506  *	modules, it will then attempt to load a module of the same name or
507  *	alias.  If that fails it will send a query to any loaded crypto manager
508  *	to construct an algorithm on the fly.  A refcount is grabbed on the
509  *	algorithm which is then associated with the new transform.
510  *
511  *	The returned transform is of a non-determinate type.  Most people
512  *	should use one of the more specific allocation functions such as
513  *	crypto_alloc_blkcipher.
514  *
515  *	In case of error the return value is an error pointer.
516  */
517 struct crypto_tfm *crypto_alloc_tfm(const char *alg_name,
518 				    const struct crypto_type *frontend,
519 				    u32 type, u32 mask)
520 {
521 	struct crypto_alg *(*lookup)(const char *name, u32 type, u32 mask);
522 	struct crypto_tfm *tfm;
523 	int err;
524 
525 	type &= frontend->maskclear;
526 	mask &= frontend->maskclear;
527 	type |= frontend->type;
528 	mask |= frontend->maskset;
529 
530 	lookup = frontend->lookup ?: crypto_alg_mod_lookup;
531 
532 	for (;;) {
533 		struct crypto_alg *alg;
534 
535 		alg = lookup(alg_name, type, mask);
536 		if (IS_ERR(alg)) {
537 			err = PTR_ERR(alg);
538 			goto err;
539 		}
540 
541 		tfm = crypto_create_tfm(alg, frontend);
542 		if (!IS_ERR(tfm))
543 			return tfm;
544 
545 		crypto_mod_put(alg);
546 		err = PTR_ERR(tfm);
547 
548 err:
549 		if (err != -EAGAIN)
550 			break;
551 		if (signal_pending(current)) {
552 			err = -EINTR;
553 			break;
554 		}
555 	}
556 
557 	return ERR_PTR(err);
558 }
559 EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
560 
561 /*
562  *	crypto_destroy_tfm - Free crypto transform
563  *	@mem: Start of tfm slab
564  *	@tfm: Transform to free
565  *
566  *	This function frees up the transform and any associated resources,
567  *	then drops the refcount on the associated algorithm.
568  */
569 void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
570 {
571 	struct crypto_alg *alg;
572 	int size;
573 
574 	if (unlikely(!mem))
575 		return;
576 
577 	alg = tfm->__crt_alg;
578 	size = ksize(mem);
579 
580 	if (!tfm->exit && alg->cra_exit)
581 		alg->cra_exit(tfm);
582 	crypto_exit_ops(tfm);
583 	crypto_mod_put(alg);
584 	memset(mem, 0, size);
585 	kfree(mem);
586 }
587 EXPORT_SYMBOL_GPL(crypto_destroy_tfm);
588 
589 int crypto_has_alg(const char *name, u32 type, u32 mask)
590 {
591 	int ret = 0;
592 	struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
593 
594 	if (!IS_ERR(alg)) {
595 		crypto_mod_put(alg);
596 		ret = 1;
597 	}
598 
599 	return ret;
600 }
601 EXPORT_SYMBOL_GPL(crypto_has_alg);
602 
603 MODULE_DESCRIPTION("Cryptographic core API");
604 MODULE_LICENSE("GPL");
605