xref: /openbmc/linux/crypto/api.c (revision a1e58bbd) 
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 struct crypto_alg *__crypto_alg_lookup(const char *name, u32 type, 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 		    ((struct crypto_larval *)q)->mask != mask)
74 			continue;
75 
76 		exact = !strcmp(q->cra_driver_name, name);
77 		fuzzy = !strcmp(q->cra_name, name);
78 		if (!exact && !(fuzzy && q->cra_priority > best))
79 			continue;
80 
81 		if (unlikely(!crypto_mod_get(q)))
82 			continue;
83 
84 		best = q->cra_priority;
85 		if (alg)
86 			crypto_mod_put(alg);
87 		alg = q;
88 
89 		if (exact)
90 			break;
91 	}
92 
93 	return alg;
94 }
95 EXPORT_SYMBOL_GPL(__crypto_alg_lookup);
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 static struct crypto_alg *crypto_larval_alloc(const char *name, u32 type,
108 					      u32 mask)
109 {
110 	struct crypto_alg *alg;
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 	atomic_set(&larval->alg.cra_refcnt, 2);
123 	strlcpy(larval->alg.cra_name, name, CRYPTO_MAX_ALG_NAME);
124 	init_completion(&larval->completion);
125 
126 	down_write(&crypto_alg_sem);
127 	alg = __crypto_alg_lookup(name, type, mask);
128 	if (!alg) {
129 		alg = &larval->alg;
130 		list_add(&alg->cra_list, &crypto_alg_list);
131 	}
132 	up_write(&crypto_alg_sem);
133 
134 	if (alg != &larval->alg)
135 		kfree(larval);
136 
137 	return alg;
138 }
139 
140 void crypto_larval_kill(struct crypto_alg *alg)
141 {
142 	struct crypto_larval *larval = (void *)alg;
143 
144 	down_write(&crypto_alg_sem);
145 	list_del(&alg->cra_list);
146 	up_write(&crypto_alg_sem);
147 	complete_all(&larval->completion);
148 	crypto_alg_put(alg);
149 }
150 EXPORT_SYMBOL_GPL(crypto_larval_kill);
151 
152 static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg)
153 {
154 	struct crypto_larval *larval = (void *)alg;
155 
156 	wait_for_completion_interruptible_timeout(&larval->completion, 60 * HZ);
157 	alg = larval->adult;
158 	if (alg) {
159 		if (!crypto_mod_get(alg))
160 			alg = ERR_PTR(-EAGAIN);
161 	} else
162 		alg = ERR_PTR(-ENOENT);
163 	crypto_mod_put(&larval->alg);
164 
165 	return alg;
166 }
167 
168 static struct crypto_alg *crypto_alg_lookup(const char *name, u32 type,
169 					    u32 mask)
170 {
171 	struct crypto_alg *alg;
172 
173 	down_read(&crypto_alg_sem);
174 	alg = __crypto_alg_lookup(name, type, mask);
175 	up_read(&crypto_alg_sem);
176 
177 	return alg;
178 }
179 
180 struct crypto_alg *crypto_larval_lookup(const char *name, u32 type, u32 mask)
181 {
182 	struct crypto_alg *alg;
183 
184 	if (!name)
185 		return ERR_PTR(-ENOENT);
186 
187 	mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
188 	type &= mask;
189 
190 	alg = try_then_request_module(crypto_alg_lookup(name, type, mask),
191 				      name);
192 	if (alg)
193 		return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
194 
195 	return crypto_larval_alloc(name, type, mask);
196 }
197 EXPORT_SYMBOL_GPL(crypto_larval_lookup);
198 
199 struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
200 {
201 	struct crypto_alg *alg;
202 	struct crypto_alg *larval;
203 	int ok;
204 
205 	larval = crypto_larval_lookup(name, type, mask);
206 	if (IS_ERR(larval) || !crypto_is_larval(larval))
207 		return larval;
208 
209 	ok = crypto_notify(CRYPTO_MSG_ALG_REQUEST, larval);
210 	if (ok == NOTIFY_DONE) {
211 		request_module("cryptomgr");
212 		ok = crypto_notify(CRYPTO_MSG_ALG_REQUEST, larval);
213 	}
214 
215 	if (ok == NOTIFY_STOP)
216 		alg = crypto_larval_wait(larval);
217 	else {
218 		crypto_mod_put(larval);
219 		alg = ERR_PTR(-ENOENT);
220 	}
221 	crypto_larval_kill(larval);
222 	return alg;
223 }
224 EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
225 
226 static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
227 {
228 	const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
229 
230 	if (type_obj)
231 		return type_obj->init(tfm, type, mask);
232 
233 	switch (crypto_tfm_alg_type(tfm)) {
234 	case CRYPTO_ALG_TYPE_CIPHER:
235 		return crypto_init_cipher_ops(tfm);
236 
237 	case CRYPTO_ALG_TYPE_DIGEST:
238 		return crypto_init_digest_ops(tfm);
239 
240 	case CRYPTO_ALG_TYPE_COMPRESS:
241 		return crypto_init_compress_ops(tfm);
242 
243 	default:
244 		break;
245 	}
246 
247 	BUG();
248 	return -EINVAL;
249 }
250 
251 static void crypto_exit_ops(struct crypto_tfm *tfm)
252 {
253 	const struct crypto_type *type = tfm->__crt_alg->cra_type;
254 
255 	if (type) {
256 		if (type->exit)
257 			type->exit(tfm);
258 		return;
259 	}
260 
261 	switch (crypto_tfm_alg_type(tfm)) {
262 	case CRYPTO_ALG_TYPE_CIPHER:
263 		crypto_exit_cipher_ops(tfm);
264 		break;
265 
266 	case CRYPTO_ALG_TYPE_DIGEST:
267 		crypto_exit_digest_ops(tfm);
268 		break;
269 
270 	case CRYPTO_ALG_TYPE_COMPRESS:
271 		crypto_exit_compress_ops(tfm);
272 		break;
273 
274 	default:
275 		BUG();
276 
277 	}
278 }
279 
280 static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
281 {
282 	const struct crypto_type *type_obj = alg->cra_type;
283 	unsigned int len;
284 
285 	len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
286 	if (type_obj)
287 		return len + type_obj->ctxsize(alg, type, mask);
288 
289 	switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
290 	default:
291 		BUG();
292 
293 	case CRYPTO_ALG_TYPE_CIPHER:
294 		len += crypto_cipher_ctxsize(alg);
295 		break;
296 
297 	case CRYPTO_ALG_TYPE_DIGEST:
298 		len += crypto_digest_ctxsize(alg);
299 		break;
300 
301 	case CRYPTO_ALG_TYPE_COMPRESS:
302 		len += crypto_compress_ctxsize(alg);
303 		break;
304 	}
305 
306 	return len;
307 }
308 
309 void crypto_shoot_alg(struct crypto_alg *alg)
310 {
311 	down_write(&crypto_alg_sem);
312 	alg->cra_flags |= CRYPTO_ALG_DYING;
313 	up_write(&crypto_alg_sem);
314 }
315 EXPORT_SYMBOL_GPL(crypto_shoot_alg);
316 
317 struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
318 				      u32 mask)
319 {
320 	struct crypto_tfm *tfm = NULL;
321 	unsigned int tfm_size;
322 	int err = -ENOMEM;
323 
324 	tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
325 	tfm = kzalloc(tfm_size, GFP_KERNEL);
326 	if (tfm == NULL)
327 		goto out_err;
328 
329 	tfm->__crt_alg = alg;
330 
331 	err = crypto_init_ops(tfm, type, mask);
332 	if (err)
333 		goto out_free_tfm;
334 
335 	if (alg->cra_init && (err = alg->cra_init(tfm))) {
336 		if (err == -EAGAIN)
337 			crypto_shoot_alg(alg);
338 		goto cra_init_failed;
339 	}
340 
341 	goto out;
342 
343 cra_init_failed:
344 	crypto_exit_ops(tfm);
345 out_free_tfm:
346 	kfree(tfm);
347 out_err:
348 	tfm = ERR_PTR(err);
349 out:
350 	return tfm;
351 }
352 EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
353 
354 /*
355  *	crypto_alloc_base - Locate algorithm and allocate transform
356  *	@alg_name: Name of algorithm
357  *	@type: Type of algorithm
358  *	@mask: Mask for type comparison
359  *
360  *	crypto_alloc_base() will first attempt to locate an already loaded
361  *	algorithm.  If that fails and the kernel supports dynamically loadable
362  *	modules, it will then attempt to load a module of the same name or
363  *	alias.  If that fails it will send a query to any loaded crypto manager
364  *	to construct an algorithm on the fly.  A refcount is grabbed on the
365  *	algorithm which is then associated with the new transform.
366  *
367  *	The returned transform is of a non-determinate type.  Most people
368  *	should use one of the more specific allocation functions such as
369  *	crypto_alloc_blkcipher.
370  *
371  *	In case of error the return value is an error pointer.
372  */
373 struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
374 {
375 	struct crypto_tfm *tfm;
376 	int err;
377 
378 	for (;;) {
379 		struct crypto_alg *alg;
380 
381 		alg = crypto_alg_mod_lookup(alg_name, type, mask);
382 		if (IS_ERR(alg)) {
383 			err = PTR_ERR(alg);
384 			goto err;
385 		}
386 
387 		tfm = __crypto_alloc_tfm(alg, type, mask);
388 		if (!IS_ERR(tfm))
389 			return tfm;
390 
391 		crypto_mod_put(alg);
392 		err = PTR_ERR(tfm);
393 
394 err:
395 		if (err != -EAGAIN)
396 			break;
397 		if (signal_pending(current)) {
398 			err = -EINTR;
399 			break;
400 		}
401 	}
402 
403 	return ERR_PTR(err);
404 }
405 EXPORT_SYMBOL_GPL(crypto_alloc_base);
406 
407 /*
408  *	crypto_free_tfm - Free crypto transform
409  *	@tfm: Transform to free
410  *
411  *	crypto_free_tfm() frees up the transform and any associated resources,
412  *	then drops the refcount on the associated algorithm.
413  */
414 void crypto_free_tfm(struct crypto_tfm *tfm)
415 {
416 	struct crypto_alg *alg;
417 	int size;
418 
419 	if (unlikely(!tfm))
420 		return;
421 
422 	alg = tfm->__crt_alg;
423 	size = sizeof(*tfm) + alg->cra_ctxsize;
424 
425 	if (alg->cra_exit)
426 		alg->cra_exit(tfm);
427 	crypto_exit_ops(tfm);
428 	crypto_mod_put(alg);
429 	memset(tfm, 0, size);
430 	kfree(tfm);
431 }
432 
433 EXPORT_SYMBOL_GPL(crypto_free_tfm);
434 
435 int crypto_has_alg(const char *name, u32 type, u32 mask)
436 {
437 	int ret = 0;
438 	struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
439 
440 	if (!IS_ERR(alg)) {
441 		crypto_mod_put(alg);
442 		ret = 1;
443 	}
444 
445 	return ret;
446 }
447 EXPORT_SYMBOL_GPL(crypto_has_alg);
448