xref: /openbmc/linux/crypto/api.c (revision 7dd65feb) 
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 
325 static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
326 {
327 	const struct crypto_type *type_obj = alg->cra_type;
328 	unsigned int len;
329 
330 	len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
331 	if (type_obj)
332 		return len + type_obj->ctxsize(alg, type, mask);
333 
334 	switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
335 	default:
336 		BUG();
337 
338 	case CRYPTO_ALG_TYPE_CIPHER:
339 		len += crypto_cipher_ctxsize(alg);
340 		break;
341 
342 	case CRYPTO_ALG_TYPE_COMPRESS:
343 		len += crypto_compress_ctxsize(alg);
344 		break;
345 	}
346 
347 	return len;
348 }
349 
350 void crypto_shoot_alg(struct crypto_alg *alg)
351 {
352 	down_write(&crypto_alg_sem);
353 	alg->cra_flags |= CRYPTO_ALG_DYING;
354 	up_write(&crypto_alg_sem);
355 }
356 EXPORT_SYMBOL_GPL(crypto_shoot_alg);
357 
358 struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
359 				      u32 mask)
360 {
361 	struct crypto_tfm *tfm = NULL;
362 	unsigned int tfm_size;
363 	int err = -ENOMEM;
364 
365 	tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
366 	tfm = kzalloc(tfm_size, GFP_KERNEL);
367 	if (tfm == NULL)
368 		goto out_err;
369 
370 	tfm->__crt_alg = alg;
371 
372 	err = crypto_init_ops(tfm, type, mask);
373 	if (err)
374 		goto out_free_tfm;
375 
376 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
377 		goto cra_init_failed;
378 
379 	goto out;
380 
381 cra_init_failed:
382 	crypto_exit_ops(tfm);
383 out_free_tfm:
384 	if (err == -EAGAIN)
385 		crypto_shoot_alg(alg);
386 	kfree(tfm);
387 out_err:
388 	tfm = ERR_PTR(err);
389 out:
390 	return tfm;
391 }
392 EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
393 
394 /*
395  *	crypto_alloc_base - Locate algorithm and allocate transform
396  *	@alg_name: Name of algorithm
397  *	@type: Type of algorithm
398  *	@mask: Mask for type comparison
399  *
400  *	This function should not be used by new algorithm types.
401  *	Plesae use crypto_alloc_tfm instead.
402  *
403  *	crypto_alloc_base() will first attempt to locate an already loaded
404  *	algorithm.  If that fails and the kernel supports dynamically loadable
405  *	modules, it will then attempt to load a module of the same name or
406  *	alias.  If that fails it will send a query to any loaded crypto manager
407  *	to construct an algorithm on the fly.  A refcount is grabbed on the
408  *	algorithm which is then associated with the new transform.
409  *
410  *	The returned transform is of a non-determinate type.  Most people
411  *	should use one of the more specific allocation functions such as
412  *	crypto_alloc_blkcipher.
413  *
414  *	In case of error the return value is an error pointer.
415  */
416 struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
417 {
418 	struct crypto_tfm *tfm;
419 	int err;
420 
421 	for (;;) {
422 		struct crypto_alg *alg;
423 
424 		alg = crypto_alg_mod_lookup(alg_name, type, mask);
425 		if (IS_ERR(alg)) {
426 			err = PTR_ERR(alg);
427 			goto err;
428 		}
429 
430 		tfm = __crypto_alloc_tfm(alg, type, mask);
431 		if (!IS_ERR(tfm))
432 			return tfm;
433 
434 		crypto_mod_put(alg);
435 		err = PTR_ERR(tfm);
436 
437 err:
438 		if (err != -EAGAIN)
439 			break;
440 		if (signal_pending(current)) {
441 			err = -EINTR;
442 			break;
443 		}
444 	}
445 
446 	return ERR_PTR(err);
447 }
448 EXPORT_SYMBOL_GPL(crypto_alloc_base);
449 
450 void *crypto_create_tfm(struct crypto_alg *alg,
451 			const struct crypto_type *frontend)
452 {
453 	char *mem;
454 	struct crypto_tfm *tfm = NULL;
455 	unsigned int tfmsize;
456 	unsigned int total;
457 	int err = -ENOMEM;
458 
459 	tfmsize = frontend->tfmsize;
460 	total = tfmsize + sizeof(*tfm) + frontend->extsize(alg);
461 
462 	mem = kzalloc(total, GFP_KERNEL);
463 	if (mem == NULL)
464 		goto out_err;
465 
466 	tfm = (struct crypto_tfm *)(mem + tfmsize);
467 	tfm->__crt_alg = alg;
468 
469 	err = frontend->init_tfm(tfm);
470 	if (err)
471 		goto out_free_tfm;
472 
473 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
474 		goto cra_init_failed;
475 
476 	goto out;
477 
478 cra_init_failed:
479 	crypto_exit_ops(tfm);
480 out_free_tfm:
481 	if (err == -EAGAIN)
482 		crypto_shoot_alg(alg);
483 	kfree(mem);
484 out_err:
485 	mem = ERR_PTR(err);
486 out:
487 	return mem;
488 }
489 EXPORT_SYMBOL_GPL(crypto_create_tfm);
490 
491 struct crypto_alg *crypto_find_alg(const char *alg_name,
492 				   const struct crypto_type *frontend,
493 				   u32 type, u32 mask)
494 {
495 	struct crypto_alg *(*lookup)(const char *name, u32 type, u32 mask) =
496 		crypto_alg_mod_lookup;
497 
498 	if (frontend) {
499 		type &= frontend->maskclear;
500 		mask &= frontend->maskclear;
501 		type |= frontend->type;
502 		mask |= frontend->maskset;
503 
504 		if (frontend->lookup)
505 			lookup = frontend->lookup;
506 	}
507 
508 	return lookup(alg_name, type, mask);
509 }
510 EXPORT_SYMBOL_GPL(crypto_find_alg);
511 
512 /*
513  *	crypto_alloc_tfm - Locate algorithm and allocate transform
514  *	@alg_name: Name of algorithm
515  *	@frontend: Frontend algorithm type
516  *	@type: Type of algorithm
517  *	@mask: Mask for type comparison
518  *
519  *	crypto_alloc_tfm() will first attempt to locate an already loaded
520  *	algorithm.  If that fails and the kernel supports dynamically loadable
521  *	modules, it will then attempt to load a module of the same name or
522  *	alias.  If that fails it will send a query to any loaded crypto manager
523  *	to construct an algorithm on the fly.  A refcount is grabbed on the
524  *	algorithm which is then associated with the new transform.
525  *
526  *	The returned transform is of a non-determinate type.  Most people
527  *	should use one of the more specific allocation functions such as
528  *	crypto_alloc_blkcipher.
529  *
530  *	In case of error the return value is an error pointer.
531  */
532 void *crypto_alloc_tfm(const char *alg_name,
533 		       const struct crypto_type *frontend, u32 type, u32 mask)
534 {
535 	void *tfm;
536 	int err;
537 
538 	for (;;) {
539 		struct crypto_alg *alg;
540 
541 		alg = crypto_find_alg(alg_name, frontend, type, mask);
542 		if (IS_ERR(alg)) {
543 			err = PTR_ERR(alg);
544 			goto err;
545 		}
546 
547 		tfm = crypto_create_tfm(alg, frontend);
548 		if (!IS_ERR(tfm))
549 			return tfm;
550 
551 		crypto_mod_put(alg);
552 		err = PTR_ERR(tfm);
553 
554 err:
555 		if (err != -EAGAIN)
556 			break;
557 		if (signal_pending(current)) {
558 			err = -EINTR;
559 			break;
560 		}
561 	}
562 
563 	return ERR_PTR(err);
564 }
565 EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
566 
567 /*
568  *	crypto_destroy_tfm - Free crypto transform
569  *	@mem: Start of tfm slab
570  *	@tfm: Transform to free
571  *
572  *	This function frees up the transform and any associated resources,
573  *	then drops the refcount on the associated algorithm.
574  */
575 void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
576 {
577 	struct crypto_alg *alg;
578 
579 	if (unlikely(!mem))
580 		return;
581 
582 	alg = tfm->__crt_alg;
583 
584 	if (!tfm->exit && alg->cra_exit)
585 		alg->cra_exit(tfm);
586 	crypto_exit_ops(tfm);
587 	crypto_mod_put(alg);
588 	kzfree(mem);
589 }
590 EXPORT_SYMBOL_GPL(crypto_destroy_tfm);
591 
592 int crypto_has_alg(const char *name, u32 type, u32 mask)
593 {
594 	int ret = 0;
595 	struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
596 
597 	if (!IS_ERR(alg)) {
598 		crypto_mod_put(alg);
599 		ret = 1;
600 	}
601 
602 	return ret;
603 }
604 EXPORT_SYMBOL_GPL(crypto_has_alg);
605 
606 MODULE_DESCRIPTION("Cryptographic core API");
607 MODULE_LICENSE("GPL");
608