xref: /openbmc/linux/crypto/api.c (revision 68198dca)
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/signal.h>
25 #include <linux/slab.h>
26 #include <linux/string.h>
27 #include <linux/completion.h>
28 #include "internal.h"
29 
30 LIST_HEAD(crypto_alg_list);
31 EXPORT_SYMBOL_GPL(crypto_alg_list);
32 DECLARE_RWSEM(crypto_alg_sem);
33 EXPORT_SYMBOL_GPL(crypto_alg_sem);
34 
35 BLOCKING_NOTIFIER_HEAD(crypto_chain);
36 EXPORT_SYMBOL_GPL(crypto_chain);
37 
38 static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg);
39 
40 struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)
41 {
42 	return try_module_get(alg->cra_module) ? crypto_alg_get(alg) : NULL;
43 }
44 EXPORT_SYMBOL_GPL(crypto_mod_get);
45 
46 void crypto_mod_put(struct crypto_alg *alg)
47 {
48 	struct module *module = alg->cra_module;
49 
50 	crypto_alg_put(alg);
51 	module_put(module);
52 }
53 EXPORT_SYMBOL_GPL(crypto_mod_put);
54 
55 static inline int crypto_is_test_larval(struct crypto_larval *larval)
56 {
57 	return larval->alg.cra_driver_name[0];
58 }
59 
60 static struct crypto_alg *__crypto_alg_lookup(const char *name, u32 type,
61 					      u32 mask)
62 {
63 	struct crypto_alg *q, *alg = NULL;
64 	int best = -2;
65 
66 	list_for_each_entry(q, &crypto_alg_list, cra_list) {
67 		int exact, fuzzy;
68 
69 		if (crypto_is_moribund(q))
70 			continue;
71 
72 		if ((q->cra_flags ^ type) & mask)
73 			continue;
74 
75 		if (crypto_is_larval(q) &&
76 		    !crypto_is_test_larval((struct crypto_larval *)q) &&
77 		    ((struct crypto_larval *)q)->mask != mask)
78 			continue;
79 
80 		exact = !strcmp(q->cra_driver_name, name);
81 		fuzzy = !strcmp(q->cra_name, name);
82 		if (!exact && !(fuzzy && q->cra_priority > best))
83 			continue;
84 
85 		if (unlikely(!crypto_mod_get(q)))
86 			continue;
87 
88 		best = q->cra_priority;
89 		if (alg)
90 			crypto_mod_put(alg);
91 		alg = q;
92 
93 		if (exact)
94 			break;
95 	}
96 
97 	return alg;
98 }
99 
100 static void crypto_larval_destroy(struct crypto_alg *alg)
101 {
102 	struct crypto_larval *larval = (void *)alg;
103 
104 	BUG_ON(!crypto_is_larval(alg));
105 	if (larval->adult)
106 		crypto_mod_put(larval->adult);
107 	kfree(larval);
108 }
109 
110 struct crypto_larval *crypto_larval_alloc(const char *name, u32 type, u32 mask)
111 {
112 	struct crypto_larval *larval;
113 
114 	larval = kzalloc(sizeof(*larval), GFP_KERNEL);
115 	if (!larval)
116 		return ERR_PTR(-ENOMEM);
117 
118 	larval->mask = mask;
119 	larval->alg.cra_flags = CRYPTO_ALG_LARVAL | type;
120 	larval->alg.cra_priority = -1;
121 	larval->alg.cra_destroy = crypto_larval_destroy;
122 
123 	strlcpy(larval->alg.cra_name, name, CRYPTO_MAX_ALG_NAME);
124 	init_completion(&larval->completion);
125 
126 	return larval;
127 }
128 EXPORT_SYMBOL_GPL(crypto_larval_alloc);
129 
130 static struct crypto_alg *crypto_larval_add(const char *name, u32 type,
131 					    u32 mask)
132 {
133 	struct crypto_alg *alg;
134 	struct crypto_larval *larval;
135 
136 	larval = crypto_larval_alloc(name, type, mask);
137 	if (IS_ERR(larval))
138 		return ERR_CAST(larval);
139 
140 	atomic_set(&larval->alg.cra_refcnt, 2);
141 
142 	down_write(&crypto_alg_sem);
143 	alg = __crypto_alg_lookup(name, type, mask);
144 	if (!alg) {
145 		alg = &larval->alg;
146 		list_add(&alg->cra_list, &crypto_alg_list);
147 	}
148 	up_write(&crypto_alg_sem);
149 
150 	if (alg != &larval->alg) {
151 		kfree(larval);
152 		if (crypto_is_larval(alg))
153 			alg = crypto_larval_wait(alg);
154 	}
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_killable_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 	type &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
216 	mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
217 
218 	alg = crypto_alg_lookup(name, type, mask);
219 	if (!alg) {
220 		request_module("crypto-%s", name);
221 
222 		if (!((type ^ CRYPTO_ALG_NEED_FALLBACK) & mask &
223 		      CRYPTO_ALG_NEED_FALLBACK))
224 			request_module("crypto-%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 	/*
262 	 * If the internal flag is set for a cipher, require a caller to
263 	 * to invoke the cipher with the internal flag to use that cipher.
264 	 * Also, if a caller wants to allocate a cipher that may or may
265 	 * not be an internal cipher, use type | CRYPTO_ALG_INTERNAL and
266 	 * !(mask & CRYPTO_ALG_INTERNAL).
267 	 */
268 	if (!((type | mask) & CRYPTO_ALG_INTERNAL))
269 		mask |= CRYPTO_ALG_INTERNAL;
270 
271 	larval = crypto_larval_lookup(name, type, mask);
272 	if (IS_ERR(larval) || !crypto_is_larval(larval))
273 		return larval;
274 
275 	ok = crypto_probing_notify(CRYPTO_MSG_ALG_REQUEST, larval);
276 
277 	if (ok == NOTIFY_STOP)
278 		alg = crypto_larval_wait(larval);
279 	else {
280 		crypto_mod_put(larval);
281 		alg = ERR_PTR(-ENOENT);
282 	}
283 	crypto_larval_kill(larval);
284 	return alg;
285 }
286 EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
287 
288 static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
289 {
290 	const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
291 
292 	if (type_obj)
293 		return type_obj->init(tfm, type, mask);
294 
295 	switch (crypto_tfm_alg_type(tfm)) {
296 	case CRYPTO_ALG_TYPE_CIPHER:
297 		return crypto_init_cipher_ops(tfm);
298 
299 	case CRYPTO_ALG_TYPE_COMPRESS:
300 		return crypto_init_compress_ops(tfm);
301 
302 	default:
303 		break;
304 	}
305 
306 	BUG();
307 	return -EINVAL;
308 }
309 
310 static void crypto_exit_ops(struct crypto_tfm *tfm)
311 {
312 	const struct crypto_type *type = tfm->__crt_alg->cra_type;
313 
314 	if (type && tfm->exit)
315 		tfm->exit(tfm);
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 (fatal_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 (fatal_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 void crypto_req_done(struct crypto_async_request *req, int err)
600 {
601 	struct crypto_wait *wait = req->data;
602 
603 	if (err == -EINPROGRESS)
604 		return;
605 
606 	wait->err = err;
607 	complete(&wait->completion);
608 }
609 EXPORT_SYMBOL_GPL(crypto_req_done);
610 
611 MODULE_DESCRIPTION("Cryptographic core API");
612 MODULE_LICENSE("GPL");
613