xref: /openbmc/linux/crypto/api.c (revision b34e08d5) 
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 struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg);
38 
39 struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)
40 {
41 	return try_module_get(alg->cra_module) ? crypto_alg_get(alg) : NULL;
42 }
43 EXPORT_SYMBOL_GPL(crypto_mod_get);
44 
45 void crypto_mod_put(struct crypto_alg *alg)
46 {
47 	struct module *module = alg->cra_module;
48 
49 	crypto_alg_put(alg);
50 	module_put(module);
51 }
52 EXPORT_SYMBOL_GPL(crypto_mod_put);
53 
54 static inline int crypto_is_test_larval(struct crypto_larval *larval)
55 {
56 	return larval->alg.cra_driver_name[0];
57 }
58 
59 static struct crypto_alg *__crypto_alg_lookup(const char *name, u32 type,
60 					      u32 mask)
61 {
62 	struct crypto_alg *q, *alg = NULL;
63 	int best = -2;
64 
65 	list_for_each_entry(q, &crypto_alg_list, cra_list) {
66 		int exact, fuzzy;
67 
68 		if (crypto_is_moribund(q))
69 			continue;
70 
71 		if ((q->cra_flags ^ type) & mask)
72 			continue;
73 
74 		if (crypto_is_larval(q) &&
75 		    !crypto_is_test_larval((struct crypto_larval *)q) &&
76 		    ((struct crypto_larval *)q)->mask != mask)
77 			continue;
78 
79 		exact = !strcmp(q->cra_driver_name, name);
80 		fuzzy = !strcmp(q->cra_name, name);
81 		if (!exact && !(fuzzy && q->cra_priority > best))
82 			continue;
83 
84 		if (unlikely(!crypto_mod_get(q)))
85 			continue;
86 
87 		best = q->cra_priority;
88 		if (alg)
89 			crypto_mod_put(alg);
90 		alg = q;
91 
92 		if (exact)
93 			break;
94 	}
95 
96 	return alg;
97 }
98 
99 static void crypto_larval_destroy(struct crypto_alg *alg)
100 {
101 	struct crypto_larval *larval = (void *)alg;
102 
103 	BUG_ON(!crypto_is_larval(alg));
104 	if (larval->adult)
105 		crypto_mod_put(larval->adult);
106 	kfree(larval);
107 }
108 
109 struct crypto_larval *crypto_larval_alloc(const char *name, u32 type, u32 mask)
110 {
111 	struct crypto_larval *larval;
112 
113 	larval = kzalloc(sizeof(*larval), GFP_KERNEL);
114 	if (!larval)
115 		return ERR_PTR(-ENOMEM);
116 
117 	larval->mask = mask;
118 	larval->alg.cra_flags = CRYPTO_ALG_LARVAL | type;
119 	larval->alg.cra_priority = -1;
120 	larval->alg.cra_destroy = crypto_larval_destroy;
121 
122 	strlcpy(larval->alg.cra_name, name, CRYPTO_MAX_ALG_NAME);
123 	init_completion(&larval->completion);
124 
125 	return larval;
126 }
127 EXPORT_SYMBOL_GPL(crypto_larval_alloc);
128 
129 static struct crypto_alg *crypto_larval_add(const char *name, u32 type,
130 					    u32 mask)
131 {
132 	struct crypto_alg *alg;
133 	struct crypto_larval *larval;
134 
135 	larval = crypto_larval_alloc(name, type, mask);
136 	if (IS_ERR(larval))
137 		return ERR_CAST(larval);
138 
139 	atomic_set(&larval->alg.cra_refcnt, 2);
140 
141 	down_write(&crypto_alg_sem);
142 	alg = __crypto_alg_lookup(name, type, mask);
143 	if (!alg) {
144 		alg = &larval->alg;
145 		list_add(&alg->cra_list, &crypto_alg_list);
146 	}
147 	up_write(&crypto_alg_sem);
148 
149 	if (alg != &larval->alg) {
150 		kfree(larval);
151 		if (crypto_is_larval(alg))
152 			alg = crypto_larval_wait(alg);
153 	}
154 
155 	return alg;
156 }
157 
158 void crypto_larval_kill(struct crypto_alg *alg)
159 {
160 	struct crypto_larval *larval = (void *)alg;
161 
162 	down_write(&crypto_alg_sem);
163 	list_del(&alg->cra_list);
164 	up_write(&crypto_alg_sem);
165 	complete_all(&larval->completion);
166 	crypto_alg_put(alg);
167 }
168 EXPORT_SYMBOL_GPL(crypto_larval_kill);
169 
170 static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg)
171 {
172 	struct crypto_larval *larval = (void *)alg;
173 	long timeout;
174 
175 	timeout = wait_for_completion_interruptible_timeout(
176 		&larval->completion, 60 * HZ);
177 
178 	alg = larval->adult;
179 	if (timeout < 0)
180 		alg = ERR_PTR(-EINTR);
181 	else if (!timeout)
182 		alg = ERR_PTR(-ETIMEDOUT);
183 	else if (!alg)
184 		alg = ERR_PTR(-ENOENT);
185 	else if (crypto_is_test_larval(larval) &&
186 		 !(alg->cra_flags & CRYPTO_ALG_TESTED))
187 		alg = ERR_PTR(-EAGAIN);
188 	else if (!crypto_mod_get(alg))
189 		alg = ERR_PTR(-EAGAIN);
190 	crypto_mod_put(&larval->alg);
191 
192 	return alg;
193 }
194 
195 struct crypto_alg *crypto_alg_lookup(const char *name, u32 type, u32 mask)
196 {
197 	struct crypto_alg *alg;
198 
199 	down_read(&crypto_alg_sem);
200 	alg = __crypto_alg_lookup(name, type, mask);
201 	up_read(&crypto_alg_sem);
202 
203 	return alg;
204 }
205 EXPORT_SYMBOL_GPL(crypto_alg_lookup);
206 
207 struct crypto_alg *crypto_larval_lookup(const char *name, u32 type, u32 mask)
208 {
209 	struct crypto_alg *alg;
210 
211 	if (!name)
212 		return ERR_PTR(-ENOENT);
213 
214 	mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
215 	type &= mask;
216 
217 	alg = crypto_alg_lookup(name, type, mask);
218 	if (!alg) {
219 		request_module("%s", name);
220 
221 		if (!((type ^ CRYPTO_ALG_NEED_FALLBACK) & mask &
222 		      CRYPTO_ALG_NEED_FALLBACK))
223 			request_module("%s-all", name);
224 
225 		alg = crypto_alg_lookup(name, type, mask);
226 	}
227 
228 	if (alg)
229 		return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
230 
231 	return crypto_larval_add(name, type, mask);
232 }
233 EXPORT_SYMBOL_GPL(crypto_larval_lookup);
234 
235 int crypto_probing_notify(unsigned long val, void *v)
236 {
237 	int ok;
238 
239 	ok = blocking_notifier_call_chain(&crypto_chain, val, v);
240 	if (ok == NOTIFY_DONE) {
241 		request_module("cryptomgr");
242 		ok = blocking_notifier_call_chain(&crypto_chain, val, v);
243 	}
244 
245 	return ok;
246 }
247 EXPORT_SYMBOL_GPL(crypto_probing_notify);
248 
249 struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
250 {
251 	struct crypto_alg *alg;
252 	struct crypto_alg *larval;
253 	int ok;
254 
255 	if (!((type | mask) & CRYPTO_ALG_TESTED)) {
256 		type |= CRYPTO_ALG_TESTED;
257 		mask |= CRYPTO_ALG_TESTED;
258 	}
259 
260 	larval = crypto_larval_lookup(name, type, mask);
261 	if (IS_ERR(larval) || !crypto_is_larval(larval))
262 		return larval;
263 
264 	ok = crypto_probing_notify(CRYPTO_MSG_ALG_REQUEST, larval);
265 
266 	if (ok == NOTIFY_STOP)
267 		alg = crypto_larval_wait(larval);
268 	else {
269 		crypto_mod_put(larval);
270 		alg = ERR_PTR(-ENOENT);
271 	}
272 	crypto_larval_kill(larval);
273 	return alg;
274 }
275 EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
276 
277 static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
278 {
279 	const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
280 
281 	if (type_obj)
282 		return type_obj->init(tfm, type, mask);
283 
284 	switch (crypto_tfm_alg_type(tfm)) {
285 	case CRYPTO_ALG_TYPE_CIPHER:
286 		return crypto_init_cipher_ops(tfm);
287 
288 	case CRYPTO_ALG_TYPE_COMPRESS:
289 		return crypto_init_compress_ops(tfm);
290 
291 	default:
292 		break;
293 	}
294 
295 	BUG();
296 	return -EINVAL;
297 }
298 
299 static void crypto_exit_ops(struct crypto_tfm *tfm)
300 {
301 	const struct crypto_type *type = tfm->__crt_alg->cra_type;
302 
303 	if (type) {
304 		if (tfm->exit)
305 			tfm->exit(tfm);
306 		return;
307 	}
308 
309 	switch (crypto_tfm_alg_type(tfm)) {
310 	case CRYPTO_ALG_TYPE_CIPHER:
311 		crypto_exit_cipher_ops(tfm);
312 		break;
313 
314 	case CRYPTO_ALG_TYPE_COMPRESS:
315 		crypto_exit_compress_ops(tfm);
316 		break;
317 
318 	default:
319 		BUG();
320 	}
321 }
322 
323 static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
324 {
325 	const struct crypto_type *type_obj = alg->cra_type;
326 	unsigned int len;
327 
328 	len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
329 	if (type_obj)
330 		return len + type_obj->ctxsize(alg, type, mask);
331 
332 	switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
333 	default:
334 		BUG();
335 
336 	case CRYPTO_ALG_TYPE_CIPHER:
337 		len += crypto_cipher_ctxsize(alg);
338 		break;
339 
340 	case CRYPTO_ALG_TYPE_COMPRESS:
341 		len += crypto_compress_ctxsize(alg);
342 		break;
343 	}
344 
345 	return len;
346 }
347 
348 void crypto_shoot_alg(struct crypto_alg *alg)
349 {
350 	down_write(&crypto_alg_sem);
351 	alg->cra_flags |= CRYPTO_ALG_DYING;
352 	up_write(&crypto_alg_sem);
353 }
354 EXPORT_SYMBOL_GPL(crypto_shoot_alg);
355 
356 struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
357 				      u32 mask)
358 {
359 	struct crypto_tfm *tfm = NULL;
360 	unsigned int tfm_size;
361 	int err = -ENOMEM;
362 
363 	tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
364 	tfm = kzalloc(tfm_size, GFP_KERNEL);
365 	if (tfm == NULL)
366 		goto out_err;
367 
368 	tfm->__crt_alg = alg;
369 
370 	err = crypto_init_ops(tfm, type, mask);
371 	if (err)
372 		goto out_free_tfm;
373 
374 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
375 		goto cra_init_failed;
376 
377 	goto out;
378 
379 cra_init_failed:
380 	crypto_exit_ops(tfm);
381 out_free_tfm:
382 	if (err == -EAGAIN)
383 		crypto_shoot_alg(alg);
384 	kfree(tfm);
385 out_err:
386 	tfm = ERR_PTR(err);
387 out:
388 	return tfm;
389 }
390 EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
391 
392 /*
393  *	crypto_alloc_base - Locate algorithm and allocate transform
394  *	@alg_name: Name of algorithm
395  *	@type: Type of algorithm
396  *	@mask: Mask for type comparison
397  *
398  *	This function should not be used by new algorithm types.
399  *	Please use crypto_alloc_tfm instead.
400  *
401  *	crypto_alloc_base() will first attempt to locate an already loaded
402  *	algorithm.  If that fails and the kernel supports dynamically loadable
403  *	modules, it will then attempt to load a module of the same name or
404  *	alias.  If that fails it will send a query to any loaded crypto manager
405  *	to construct an algorithm on the fly.  A refcount is grabbed on the
406  *	algorithm which is then associated with the new transform.
407  *
408  *	The returned transform is of a non-determinate type.  Most people
409  *	should use one of the more specific allocation functions such as
410  *	crypto_alloc_blkcipher.
411  *
412  *	In case of error the return value is an error pointer.
413  */
414 struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
415 {
416 	struct crypto_tfm *tfm;
417 	int err;
418 
419 	for (;;) {
420 		struct crypto_alg *alg;
421 
422 		alg = crypto_alg_mod_lookup(alg_name, type, mask);
423 		if (IS_ERR(alg)) {
424 			err = PTR_ERR(alg);
425 			goto err;
426 		}
427 
428 		tfm = __crypto_alloc_tfm(alg, type, mask);
429 		if (!IS_ERR(tfm))
430 			return tfm;
431 
432 		crypto_mod_put(alg);
433 		err = PTR_ERR(tfm);
434 
435 err:
436 		if (err != -EAGAIN)
437 			break;
438 		if (signal_pending(current)) {
439 			err = -EINTR;
440 			break;
441 		}
442 	}
443 
444 	return ERR_PTR(err);
445 }
446 EXPORT_SYMBOL_GPL(crypto_alloc_base);
447 
448 void *crypto_create_tfm(struct crypto_alg *alg,
449 			const struct crypto_type *frontend)
450 {
451 	char *mem;
452 	struct crypto_tfm *tfm = NULL;
453 	unsigned int tfmsize;
454 	unsigned int total;
455 	int err = -ENOMEM;
456 
457 	tfmsize = frontend->tfmsize;
458 	total = tfmsize + sizeof(*tfm) + frontend->extsize(alg);
459 
460 	mem = kzalloc(total, GFP_KERNEL);
461 	if (mem == NULL)
462 		goto out_err;
463 
464 	tfm = (struct crypto_tfm *)(mem + tfmsize);
465 	tfm->__crt_alg = alg;
466 
467 	err = frontend->init_tfm(tfm);
468 	if (err)
469 		goto out_free_tfm;
470 
471 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
472 		goto cra_init_failed;
473 
474 	goto out;
475 
476 cra_init_failed:
477 	crypto_exit_ops(tfm);
478 out_free_tfm:
479 	if (err == -EAGAIN)
480 		crypto_shoot_alg(alg);
481 	kfree(mem);
482 out_err:
483 	mem = ERR_PTR(err);
484 out:
485 	return mem;
486 }
487 EXPORT_SYMBOL_GPL(crypto_create_tfm);
488 
489 struct crypto_alg *crypto_find_alg(const char *alg_name,
490 				   const struct crypto_type *frontend,
491 				   u32 type, u32 mask)
492 {
493 	struct crypto_alg *(*lookup)(const char *name, u32 type, u32 mask) =
494 		crypto_alg_mod_lookup;
495 
496 	if (frontend) {
497 		type &= frontend->maskclear;
498 		mask &= frontend->maskclear;
499 		type |= frontend->type;
500 		mask |= frontend->maskset;
501 
502 		if (frontend->lookup)
503 			lookup = frontend->lookup;
504 	}
505 
506 	return lookup(alg_name, type, mask);
507 }
508 EXPORT_SYMBOL_GPL(crypto_find_alg);
509 
510 /*
511  *	crypto_alloc_tfm - Locate algorithm and allocate transform
512  *	@alg_name: Name of algorithm
513  *	@frontend: Frontend algorithm type
514  *	@type: Type of algorithm
515  *	@mask: Mask for type comparison
516  *
517  *	crypto_alloc_tfm() will first attempt to locate an already loaded
518  *	algorithm.  If that fails and the kernel supports dynamically loadable
519  *	modules, it will then attempt to load a module of the same name or
520  *	alias.  If that fails it will send a query to any loaded crypto manager
521  *	to construct an algorithm on the fly.  A refcount is grabbed on the
522  *	algorithm which is then associated with the new transform.
523  *
524  *	The returned transform is of a non-determinate type.  Most people
525  *	should use one of the more specific allocation functions such as
526  *	crypto_alloc_blkcipher.
527  *
528  *	In case of error the return value is an error pointer.
529  */
530 void *crypto_alloc_tfm(const char *alg_name,
531 		       const struct crypto_type *frontend, u32 type, u32 mask)
532 {
533 	void *tfm;
534 	int err;
535 
536 	for (;;) {
537 		struct crypto_alg *alg;
538 
539 		alg = crypto_find_alg(alg_name, frontend, type, mask);
540 		if (IS_ERR(alg)) {
541 			err = PTR_ERR(alg);
542 			goto err;
543 		}
544 
545 		tfm = crypto_create_tfm(alg, frontend);
546 		if (!IS_ERR(tfm))
547 			return tfm;
548 
549 		crypto_mod_put(alg);
550 		err = PTR_ERR(tfm);
551 
552 err:
553 		if (err != -EAGAIN)
554 			break;
555 		if (signal_pending(current)) {
556 			err = -EINTR;
557 			break;
558 		}
559 	}
560 
561 	return ERR_PTR(err);
562 }
563 EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
564 
565 /*
566  *	crypto_destroy_tfm - Free crypto transform
567  *	@mem: Start of tfm slab
568  *	@tfm: Transform to free
569  *
570  *	This function frees up the transform and any associated resources,
571  *	then drops the refcount on the associated algorithm.
572  */
573 void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
574 {
575 	struct crypto_alg *alg;
576 
577 	if (unlikely(!mem))
578 		return;
579 
580 	alg = tfm->__crt_alg;
581 
582 	if (!tfm->exit && alg->cra_exit)
583 		alg->cra_exit(tfm);
584 	crypto_exit_ops(tfm);
585 	crypto_mod_put(alg);
586 	kzfree(mem);
587 }
588 EXPORT_SYMBOL_GPL(crypto_destroy_tfm);
589 
590 int crypto_has_alg(const char *name, u32 type, u32 mask)
591 {
592 	int ret = 0;
593 	struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
594 
595 	if (!IS_ERR(alg)) {
596 		crypto_mod_put(alg);
597 		ret = 1;
598 	}
599 
600 	return ret;
601 }
602 EXPORT_SYMBOL_GPL(crypto_has_alg);
603 
604 MODULE_DESCRIPTION("Cryptographic core API");
605 MODULE_LICENSE("GPL");
606