xref: /openbmc/linux/crypto/api.c (revision 70342287) 
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_COMPRESS:
290 		return crypto_init_compress_ops(tfm);
291 
292 	default:
293 		break;
294 	}
295 
296 	BUG();
297 	return -EINVAL;
298 }
299 
300 static void crypto_exit_ops(struct crypto_tfm *tfm)
301 {
302 	const struct crypto_type *type = tfm->__crt_alg->cra_type;
303 
304 	if (type) {
305 		if (tfm->exit)
306 			tfm->exit(tfm);
307 		return;
308 	}
309 
310 	switch (crypto_tfm_alg_type(tfm)) {
311 	case CRYPTO_ALG_TYPE_CIPHER:
312 		crypto_exit_cipher_ops(tfm);
313 		break;
314 
315 	case CRYPTO_ALG_TYPE_COMPRESS:
316 		crypto_exit_compress_ops(tfm);
317 		break;
318 
319 	default:
320 		BUG();
321 	}
322 }
323 
324 static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
325 {
326 	const struct crypto_type *type_obj = alg->cra_type;
327 	unsigned int len;
328 
329 	len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
330 	if (type_obj)
331 		return len + type_obj->ctxsize(alg, type, mask);
332 
333 	switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
334 	default:
335 		BUG();
336 
337 	case CRYPTO_ALG_TYPE_CIPHER:
338 		len += crypto_cipher_ctxsize(alg);
339 		break;
340 
341 	case CRYPTO_ALG_TYPE_COMPRESS:
342 		len += crypto_compress_ctxsize(alg);
343 		break;
344 	}
345 
346 	return len;
347 }
348 
349 void crypto_shoot_alg(struct crypto_alg *alg)
350 {
351 	down_write(&crypto_alg_sem);
352 	alg->cra_flags |= CRYPTO_ALG_DYING;
353 	up_write(&crypto_alg_sem);
354 }
355 EXPORT_SYMBOL_GPL(crypto_shoot_alg);
356 
357 struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
358 				      u32 mask)
359 {
360 	struct crypto_tfm *tfm = NULL;
361 	unsigned int tfm_size;
362 	int err = -ENOMEM;
363 
364 	tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
365 	tfm = kzalloc(tfm_size, GFP_KERNEL);
366 	if (tfm == NULL)
367 		goto out_err;
368 
369 	tfm->__crt_alg = alg;
370 
371 	err = crypto_init_ops(tfm, type, mask);
372 	if (err)
373 		goto out_free_tfm;
374 
375 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
376 		goto cra_init_failed;
377 
378 	goto out;
379 
380 cra_init_failed:
381 	crypto_exit_ops(tfm);
382 out_free_tfm:
383 	if (err == -EAGAIN)
384 		crypto_shoot_alg(alg);
385 	kfree(tfm);
386 out_err:
387 	tfm = ERR_PTR(err);
388 out:
389 	return tfm;
390 }
391 EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
392 
393 /*
394  *	crypto_alloc_base - Locate algorithm and allocate transform
395  *	@alg_name: Name of algorithm
396  *	@type: Type of algorithm
397  *	@mask: Mask for type comparison
398  *
399  *	This function should not be used by new algorithm types.
400  *	Plesae use crypto_alloc_tfm instead.
401  *
402  *	crypto_alloc_base() will first attempt to locate an already loaded
403  *	algorithm.  If that fails and the kernel supports dynamically loadable
404  *	modules, it will then attempt to load a module of the same name or
405  *	alias.  If that fails it will send a query to any loaded crypto manager
406  *	to construct an algorithm on the fly.  A refcount is grabbed on the
407  *	algorithm which is then associated with the new transform.
408  *
409  *	The returned transform is of a non-determinate type.  Most people
410  *	should use one of the more specific allocation functions such as
411  *	crypto_alloc_blkcipher.
412  *
413  *	In case of error the return value is an error pointer.
414  */
415 struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
416 {
417 	struct crypto_tfm *tfm;
418 	int err;
419 
420 	for (;;) {
421 		struct crypto_alg *alg;
422 
423 		alg = crypto_alg_mod_lookup(alg_name, type, mask);
424 		if (IS_ERR(alg)) {
425 			err = PTR_ERR(alg);
426 			goto err;
427 		}
428 
429 		tfm = __crypto_alloc_tfm(alg, type, mask);
430 		if (!IS_ERR(tfm))
431 			return tfm;
432 
433 		crypto_mod_put(alg);
434 		err = PTR_ERR(tfm);
435 
436 err:
437 		if (err != -EAGAIN)
438 			break;
439 		if (signal_pending(current)) {
440 			err = -EINTR;
441 			break;
442 		}
443 	}
444 
445 	return ERR_PTR(err);
446 }
447 EXPORT_SYMBOL_GPL(crypto_alloc_base);
448 
449 void *crypto_create_tfm(struct crypto_alg *alg,
450 			const struct crypto_type *frontend)
451 {
452 	char *mem;
453 	struct crypto_tfm *tfm = NULL;
454 	unsigned int tfmsize;
455 	unsigned int total;
456 	int err = -ENOMEM;
457 
458 	tfmsize = frontend->tfmsize;
459 	total = tfmsize + sizeof(*tfm) + frontend->extsize(alg);
460 
461 	mem = kzalloc(total, GFP_KERNEL);
462 	if (mem == NULL)
463 		goto out_err;
464 
465 	tfm = (struct crypto_tfm *)(mem + tfmsize);
466 	tfm->__crt_alg = alg;
467 
468 	err = frontend->init_tfm(tfm);
469 	if (err)
470 		goto out_free_tfm;
471 
472 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
473 		goto cra_init_failed;
474 
475 	goto out;
476 
477 cra_init_failed:
478 	crypto_exit_ops(tfm);
479 out_free_tfm:
480 	if (err == -EAGAIN)
481 		crypto_shoot_alg(alg);
482 	kfree(mem);
483 out_err:
484 	mem = ERR_PTR(err);
485 out:
486 	return mem;
487 }
488 EXPORT_SYMBOL_GPL(crypto_create_tfm);
489 
490 struct crypto_alg *crypto_find_alg(const char *alg_name,
491 				   const struct crypto_type *frontend,
492 				   u32 type, u32 mask)
493 {
494 	struct crypto_alg *(*lookup)(const char *name, u32 type, u32 mask) =
495 		crypto_alg_mod_lookup;
496 
497 	if (frontend) {
498 		type &= frontend->maskclear;
499 		mask &= frontend->maskclear;
500 		type |= frontend->type;
501 		mask |= frontend->maskset;
502 
503 		if (frontend->lookup)
504 			lookup = frontend->lookup;
505 	}
506 
507 	return lookup(alg_name, type, mask);
508 }
509 EXPORT_SYMBOL_GPL(crypto_find_alg);
510 
511 /*
512  *	crypto_alloc_tfm - Locate algorithm and allocate transform
513  *	@alg_name: Name of algorithm
514  *	@frontend: Frontend algorithm type
515  *	@type: Type of algorithm
516  *	@mask: Mask for type comparison
517  *
518  *	crypto_alloc_tfm() will first attempt to locate an already loaded
519  *	algorithm.  If that fails and the kernel supports dynamically loadable
520  *	modules, it will then attempt to load a module of the same name or
521  *	alias.  If that fails it will send a query to any loaded crypto manager
522  *	to construct an algorithm on the fly.  A refcount is grabbed on the
523  *	algorithm which is then associated with the new transform.
524  *
525  *	The returned transform is of a non-determinate type.  Most people
526  *	should use one of the more specific allocation functions such as
527  *	crypto_alloc_blkcipher.
528  *
529  *	In case of error the return value is an error pointer.
530  */
531 void *crypto_alloc_tfm(const char *alg_name,
532 		       const struct crypto_type *frontend, u32 type, u32 mask)
533 {
534 	void *tfm;
535 	int err;
536 
537 	for (;;) {
538 		struct crypto_alg *alg;
539 
540 		alg = crypto_find_alg(alg_name, frontend, type, mask);
541 		if (IS_ERR(alg)) {
542 			err = PTR_ERR(alg);
543 			goto err;
544 		}
545 
546 		tfm = crypto_create_tfm(alg, frontend);
547 		if (!IS_ERR(tfm))
548 			return tfm;
549 
550 		crypto_mod_put(alg);
551 		err = PTR_ERR(tfm);
552 
553 err:
554 		if (err != -EAGAIN)
555 			break;
556 		if (signal_pending(current)) {
557 			err = -EINTR;
558 			break;
559 		}
560 	}
561 
562 	return ERR_PTR(err);
563 }
564 EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
565 
566 /*
567  *	crypto_destroy_tfm - Free crypto transform
568  *	@mem: Start of tfm slab
569  *	@tfm: Transform to free
570  *
571  *	This function frees up the transform and any associated resources,
572  *	then drops the refcount on the associated algorithm.
573  */
574 void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
575 {
576 	struct crypto_alg *alg;
577 
578 	if (unlikely(!mem))
579 		return;
580 
581 	alg = tfm->__crt_alg;
582 
583 	if (!tfm->exit && alg->cra_exit)
584 		alg->cra_exit(tfm);
585 	crypto_exit_ops(tfm);
586 	crypto_mod_put(alg);
587 	kzfree(mem);
588 }
589 EXPORT_SYMBOL_GPL(crypto_destroy_tfm);
590 
591 int crypto_has_alg(const char *name, u32 type, u32 mask)
592 {
593 	int ret = 0;
594 	struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
595 
596 	if (!IS_ERR(alg)) {
597 		crypto_mod_put(alg);
598 		ret = 1;
599 	}
600 
601 	return ret;
602 }
603 EXPORT_SYMBOL_GPL(crypto_has_alg);
604 
605 MODULE_DESCRIPTION("Cryptographic core API");
606 MODULE_LICENSE("GPL");
607