xref: /openbmc/linux/crypto/api.c (revision b34081f1) 
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 struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)
38 {
39 	return try_module_get(alg->cra_module) ? crypto_alg_get(alg) : NULL;
40 }
41 EXPORT_SYMBOL_GPL(crypto_mod_get);
42 
43 void crypto_mod_put(struct crypto_alg *alg)
44 {
45 	struct module *module = alg->cra_module;
46 
47 	crypto_alg_put(alg);
48 	module_put(module);
49 }
50 EXPORT_SYMBOL_GPL(crypto_mod_put);
51 
52 static inline int crypto_is_test_larval(struct crypto_larval *larval)
53 {
54 	return larval->alg.cra_driver_name[0];
55 }
56 
57 static struct crypto_alg *__crypto_alg_lookup(const char *name, u32 type,
58 					      u32 mask)
59 {
60 	struct crypto_alg *q, *alg = NULL;
61 	int best = -2;
62 
63 	list_for_each_entry(q, &crypto_alg_list, cra_list) {
64 		int exact, fuzzy;
65 
66 		if (crypto_is_moribund(q))
67 			continue;
68 
69 		if ((q->cra_flags ^ type) & mask)
70 			continue;
71 
72 		if (crypto_is_larval(q) &&
73 		    !crypto_is_test_larval((struct crypto_larval *)q) &&
74 		    ((struct crypto_larval *)q)->mask != mask)
75 			continue;
76 
77 		exact = !strcmp(q->cra_driver_name, name);
78 		fuzzy = !strcmp(q->cra_name, name);
79 		if (!exact && !(fuzzy && q->cra_priority > best))
80 			continue;
81 
82 		if (unlikely(!crypto_mod_get(q)))
83 			continue;
84 
85 		best = q->cra_priority;
86 		if (alg)
87 			crypto_mod_put(alg);
88 		alg = q;
89 
90 		if (exact)
91 			break;
92 	}
93 
94 	return alg;
95 }
96 
97 static void crypto_larval_destroy(struct crypto_alg *alg)
98 {
99 	struct crypto_larval *larval = (void *)alg;
100 
101 	BUG_ON(!crypto_is_larval(alg));
102 	if (larval->adult)
103 		crypto_mod_put(larval->adult);
104 	kfree(larval);
105 }
106 
107 struct crypto_larval *crypto_larval_alloc(const char *name, u32 type, u32 mask)
108 {
109 	struct crypto_larval *larval;
110 
111 	larval = kzalloc(sizeof(*larval), GFP_KERNEL);
112 	if (!larval)
113 		return ERR_PTR(-ENOMEM);
114 
115 	larval->mask = mask;
116 	larval->alg.cra_flags = CRYPTO_ALG_LARVAL | type;
117 	larval->alg.cra_priority = -1;
118 	larval->alg.cra_destroy = crypto_larval_destroy;
119 
120 	strlcpy(larval->alg.cra_name, name, CRYPTO_MAX_ALG_NAME);
121 	init_completion(&larval->completion);
122 
123 	return larval;
124 }
125 EXPORT_SYMBOL_GPL(crypto_larval_alloc);
126 
127 static struct crypto_alg *crypto_larval_add(const char *name, u32 type,
128 					    u32 mask)
129 {
130 	struct crypto_alg *alg;
131 	struct crypto_larval *larval;
132 
133 	larval = crypto_larval_alloc(name, type, mask);
134 	if (IS_ERR(larval))
135 		return ERR_CAST(larval);
136 
137 	atomic_set(&larval->alg.cra_refcnt, 2);
138 
139 	down_write(&crypto_alg_sem);
140 	alg = __crypto_alg_lookup(name, type, mask);
141 	if (!alg) {
142 		alg = &larval->alg;
143 		list_add(&alg->cra_list, &crypto_alg_list);
144 	}
145 	up_write(&crypto_alg_sem);
146 
147 	if (alg != &larval->alg)
148 		kfree(larval);
149 
150 	return alg;
151 }
152 
153 void crypto_larval_kill(struct crypto_alg *alg)
154 {
155 	struct crypto_larval *larval = (void *)alg;
156 
157 	down_write(&crypto_alg_sem);
158 	list_del(&alg->cra_list);
159 	up_write(&crypto_alg_sem);
160 	complete_all(&larval->completion);
161 	crypto_alg_put(alg);
162 }
163 EXPORT_SYMBOL_GPL(crypto_larval_kill);
164 
165 static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg)
166 {
167 	struct crypto_larval *larval = (void *)alg;
168 	long timeout;
169 
170 	timeout = wait_for_completion_interruptible_timeout(
171 		&larval->completion, 60 * HZ);
172 
173 	alg = larval->adult;
174 	if (timeout < 0)
175 		alg = ERR_PTR(-EINTR);
176 	else if (!timeout)
177 		alg = ERR_PTR(-ETIMEDOUT);
178 	else if (!alg)
179 		alg = ERR_PTR(-ENOENT);
180 	else if (crypto_is_test_larval(larval) &&
181 		 !(alg->cra_flags & CRYPTO_ALG_TESTED))
182 		alg = ERR_PTR(-EAGAIN);
183 	else if (!crypto_mod_get(alg))
184 		alg = ERR_PTR(-EAGAIN);
185 	crypto_mod_put(&larval->alg);
186 
187 	return alg;
188 }
189 
190 struct crypto_alg *crypto_alg_lookup(const char *name, u32 type, u32 mask)
191 {
192 	struct crypto_alg *alg;
193 
194 	down_read(&crypto_alg_sem);
195 	alg = __crypto_alg_lookup(name, type, mask);
196 	up_read(&crypto_alg_sem);
197 
198 	return alg;
199 }
200 EXPORT_SYMBOL_GPL(crypto_alg_lookup);
201 
202 struct crypto_alg *crypto_larval_lookup(const char *name, u32 type, u32 mask)
203 {
204 	struct crypto_alg *alg;
205 
206 	if (!name)
207 		return ERR_PTR(-ENOENT);
208 
209 	mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
210 	type &= mask;
211 
212 	alg = crypto_alg_lookup(name, type, mask);
213 	if (!alg) {
214 		request_module("%s", name);
215 
216 		if (!((type ^ CRYPTO_ALG_NEED_FALLBACK) & mask &
217 		      CRYPTO_ALG_NEED_FALLBACK))
218 			request_module("%s-all", name);
219 
220 		alg = crypto_alg_lookup(name, type, mask);
221 	}
222 
223 	if (alg)
224 		return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
225 
226 	return crypto_larval_add(name, type, mask);
227 }
228 EXPORT_SYMBOL_GPL(crypto_larval_lookup);
229 
230 int crypto_probing_notify(unsigned long val, void *v)
231 {
232 	int ok;
233 
234 	ok = blocking_notifier_call_chain(&crypto_chain, val, v);
235 	if (ok == NOTIFY_DONE) {
236 		request_module("cryptomgr");
237 		ok = blocking_notifier_call_chain(&crypto_chain, val, v);
238 	}
239 
240 	return ok;
241 }
242 EXPORT_SYMBOL_GPL(crypto_probing_notify);
243 
244 struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
245 {
246 	struct crypto_alg *alg;
247 	struct crypto_alg *larval;
248 	int ok;
249 
250 	if (!((type | mask) & CRYPTO_ALG_TESTED)) {
251 		type |= CRYPTO_ALG_TESTED;
252 		mask |= CRYPTO_ALG_TESTED;
253 	}
254 
255 	larval = crypto_larval_lookup(name, type, mask);
256 	if (IS_ERR(larval) || !crypto_is_larval(larval))
257 		return larval;
258 
259 	ok = crypto_probing_notify(CRYPTO_MSG_ALG_REQUEST, larval);
260 
261 	if (ok == NOTIFY_STOP)
262 		alg = crypto_larval_wait(larval);
263 	else {
264 		crypto_mod_put(larval);
265 		alg = ERR_PTR(-ENOENT);
266 	}
267 	crypto_larval_kill(larval);
268 	return alg;
269 }
270 EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
271 
272 static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
273 {
274 	const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
275 
276 	if (type_obj)
277 		return type_obj->init(tfm, type, mask);
278 
279 	switch (crypto_tfm_alg_type(tfm)) {
280 	case CRYPTO_ALG_TYPE_CIPHER:
281 		return crypto_init_cipher_ops(tfm);
282 
283 	case CRYPTO_ALG_TYPE_COMPRESS:
284 		return crypto_init_compress_ops(tfm);
285 
286 	default:
287 		break;
288 	}
289 
290 	BUG();
291 	return -EINVAL;
292 }
293 
294 static void crypto_exit_ops(struct crypto_tfm *tfm)
295 {
296 	const struct crypto_type *type = tfm->__crt_alg->cra_type;
297 
298 	if (type) {
299 		if (tfm->exit)
300 			tfm->exit(tfm);
301 		return;
302 	}
303 
304 	switch (crypto_tfm_alg_type(tfm)) {
305 	case CRYPTO_ALG_TYPE_CIPHER:
306 		crypto_exit_cipher_ops(tfm);
307 		break;
308 
309 	case CRYPTO_ALG_TYPE_COMPRESS:
310 		crypto_exit_compress_ops(tfm);
311 		break;
312 
313 	default:
314 		BUG();
315 	}
316 }
317 
318 static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
319 {
320 	const struct crypto_type *type_obj = alg->cra_type;
321 	unsigned int len;
322 
323 	len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
324 	if (type_obj)
325 		return len + type_obj->ctxsize(alg, type, mask);
326 
327 	switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
328 	default:
329 		BUG();
330 
331 	case CRYPTO_ALG_TYPE_CIPHER:
332 		len += crypto_cipher_ctxsize(alg);
333 		break;
334 
335 	case CRYPTO_ALG_TYPE_COMPRESS:
336 		len += crypto_compress_ctxsize(alg);
337 		break;
338 	}
339 
340 	return len;
341 }
342 
343 void crypto_shoot_alg(struct crypto_alg *alg)
344 {
345 	down_write(&crypto_alg_sem);
346 	alg->cra_flags |= CRYPTO_ALG_DYING;
347 	up_write(&crypto_alg_sem);
348 }
349 EXPORT_SYMBOL_GPL(crypto_shoot_alg);
350 
351 struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
352 				      u32 mask)
353 {
354 	struct crypto_tfm *tfm = NULL;
355 	unsigned int tfm_size;
356 	int err = -ENOMEM;
357 
358 	tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
359 	tfm = kzalloc(tfm_size, GFP_KERNEL);
360 	if (tfm == NULL)
361 		goto out_err;
362 
363 	tfm->__crt_alg = alg;
364 
365 	err = crypto_init_ops(tfm, type, mask);
366 	if (err)
367 		goto out_free_tfm;
368 
369 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
370 		goto cra_init_failed;
371 
372 	goto out;
373 
374 cra_init_failed:
375 	crypto_exit_ops(tfm);
376 out_free_tfm:
377 	if (err == -EAGAIN)
378 		crypto_shoot_alg(alg);
379 	kfree(tfm);
380 out_err:
381 	tfm = ERR_PTR(err);
382 out:
383 	return tfm;
384 }
385 EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
386 
387 /*
388  *	crypto_alloc_base - Locate algorithm and allocate transform
389  *	@alg_name: Name of algorithm
390  *	@type: Type of algorithm
391  *	@mask: Mask for type comparison
392  *
393  *	This function should not be used by new algorithm types.
394  *	Please use crypto_alloc_tfm instead.
395  *
396  *	crypto_alloc_base() will first attempt to locate an already loaded
397  *	algorithm.  If that fails and the kernel supports dynamically loadable
398  *	modules, it will then attempt to load a module of the same name or
399  *	alias.  If that fails it will send a query to any loaded crypto manager
400  *	to construct an algorithm on the fly.  A refcount is grabbed on the
401  *	algorithm which is then associated with the new transform.
402  *
403  *	The returned transform is of a non-determinate type.  Most people
404  *	should use one of the more specific allocation functions such as
405  *	crypto_alloc_blkcipher.
406  *
407  *	In case of error the return value is an error pointer.
408  */
409 struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
410 {
411 	struct crypto_tfm *tfm;
412 	int err;
413 
414 	for (;;) {
415 		struct crypto_alg *alg;
416 
417 		alg = crypto_alg_mod_lookup(alg_name, type, mask);
418 		if (IS_ERR(alg)) {
419 			err = PTR_ERR(alg);
420 			goto err;
421 		}
422 
423 		tfm = __crypto_alloc_tfm(alg, type, mask);
424 		if (!IS_ERR(tfm))
425 			return tfm;
426 
427 		crypto_mod_put(alg);
428 		err = PTR_ERR(tfm);
429 
430 err:
431 		if (err != -EAGAIN)
432 			break;
433 		if (signal_pending(current)) {
434 			err = -EINTR;
435 			break;
436 		}
437 	}
438 
439 	return ERR_PTR(err);
440 }
441 EXPORT_SYMBOL_GPL(crypto_alloc_base);
442 
443 void *crypto_create_tfm(struct crypto_alg *alg,
444 			const struct crypto_type *frontend)
445 {
446 	char *mem;
447 	struct crypto_tfm *tfm = NULL;
448 	unsigned int tfmsize;
449 	unsigned int total;
450 	int err = -ENOMEM;
451 
452 	tfmsize = frontend->tfmsize;
453 	total = tfmsize + sizeof(*tfm) + frontend->extsize(alg);
454 
455 	mem = kzalloc(total, GFP_KERNEL);
456 	if (mem == NULL)
457 		goto out_err;
458 
459 	tfm = (struct crypto_tfm *)(mem + tfmsize);
460 	tfm->__crt_alg = alg;
461 
462 	err = frontend->init_tfm(tfm);
463 	if (err)
464 		goto out_free_tfm;
465 
466 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
467 		goto cra_init_failed;
468 
469 	goto out;
470 
471 cra_init_failed:
472 	crypto_exit_ops(tfm);
473 out_free_tfm:
474 	if (err == -EAGAIN)
475 		crypto_shoot_alg(alg);
476 	kfree(mem);
477 out_err:
478 	mem = ERR_PTR(err);
479 out:
480 	return mem;
481 }
482 EXPORT_SYMBOL_GPL(crypto_create_tfm);
483 
484 struct crypto_alg *crypto_find_alg(const char *alg_name,
485 				   const struct crypto_type *frontend,
486 				   u32 type, u32 mask)
487 {
488 	struct crypto_alg *(*lookup)(const char *name, u32 type, u32 mask) =
489 		crypto_alg_mod_lookup;
490 
491 	if (frontend) {
492 		type &= frontend->maskclear;
493 		mask &= frontend->maskclear;
494 		type |= frontend->type;
495 		mask |= frontend->maskset;
496 
497 		if (frontend->lookup)
498 			lookup = frontend->lookup;
499 	}
500 
501 	return lookup(alg_name, type, mask);
502 }
503 EXPORT_SYMBOL_GPL(crypto_find_alg);
504 
505 /*
506  *	crypto_alloc_tfm - Locate algorithm and allocate transform
507  *	@alg_name: Name of algorithm
508  *	@frontend: Frontend algorithm type
509  *	@type: Type of algorithm
510  *	@mask: Mask for type comparison
511  *
512  *	crypto_alloc_tfm() will first attempt to locate an already loaded
513  *	algorithm.  If that fails and the kernel supports dynamically loadable
514  *	modules, it will then attempt to load a module of the same name or
515  *	alias.  If that fails it will send a query to any loaded crypto manager
516  *	to construct an algorithm on the fly.  A refcount is grabbed on the
517  *	algorithm which is then associated with the new transform.
518  *
519  *	The returned transform is of a non-determinate type.  Most people
520  *	should use one of the more specific allocation functions such as
521  *	crypto_alloc_blkcipher.
522  *
523  *	In case of error the return value is an error pointer.
524  */
525 void *crypto_alloc_tfm(const char *alg_name,
526 		       const struct crypto_type *frontend, u32 type, u32 mask)
527 {
528 	void *tfm;
529 	int err;
530 
531 	for (;;) {
532 		struct crypto_alg *alg;
533 
534 		alg = crypto_find_alg(alg_name, frontend, type, mask);
535 		if (IS_ERR(alg)) {
536 			err = PTR_ERR(alg);
537 			goto err;
538 		}
539 
540 		tfm = crypto_create_tfm(alg, frontend);
541 		if (!IS_ERR(tfm))
542 			return tfm;
543 
544 		crypto_mod_put(alg);
545 		err = PTR_ERR(tfm);
546 
547 err:
548 		if (err != -EAGAIN)
549 			break;
550 		if (signal_pending(current)) {
551 			err = -EINTR;
552 			break;
553 		}
554 	}
555 
556 	return ERR_PTR(err);
557 }
558 EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
559 
560 /*
561  *	crypto_destroy_tfm - Free crypto transform
562  *	@mem: Start of tfm slab
563  *	@tfm: Transform to free
564  *
565  *	This function frees up the transform and any associated resources,
566  *	then drops the refcount on the associated algorithm.
567  */
568 void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
569 {
570 	struct crypto_alg *alg;
571 
572 	if (unlikely(!mem))
573 		return;
574 
575 	alg = tfm->__crt_alg;
576 
577 	if (!tfm->exit && alg->cra_exit)
578 		alg->cra_exit(tfm);
579 	crypto_exit_ops(tfm);
580 	crypto_mod_put(alg);
581 	kzfree(mem);
582 }
583 EXPORT_SYMBOL_GPL(crypto_destroy_tfm);
584 
585 int crypto_has_alg(const char *name, u32 type, u32 mask)
586 {
587 	int ret = 0;
588 	struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
589 
590 	if (!IS_ERR(alg)) {
591 		crypto_mod_put(alg);
592 		ret = 1;
593 	}
594 
595 	return ret;
596 }
597 EXPORT_SYMBOL_GPL(crypto_has_alg);
598 
599 MODULE_DESCRIPTION("Cryptographic core API");
600 MODULE_LICENSE("GPL");
601