xref: /openbmc/linux/crypto/api.c (revision c21b37f6) 
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 M�ller.
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 static 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 
151 static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg)
152 {
153 	struct crypto_larval *larval = (void *)alg;
154 
155 	wait_for_completion_interruptible_timeout(&larval->completion, 60 * HZ);
156 	alg = larval->adult;
157 	if (alg) {
158 		if (!crypto_mod_get(alg))
159 			alg = ERR_PTR(-EAGAIN);
160 	} else
161 		alg = ERR_PTR(-ENOENT);
162 	crypto_mod_put(&larval->alg);
163 
164 	return alg;
165 }
166 
167 static struct crypto_alg *crypto_alg_lookup(const char *name, u32 type,
168 					    u32 mask)
169 {
170 	struct crypto_alg *alg;
171 
172 	down_read(&crypto_alg_sem);
173 	alg = __crypto_alg_lookup(name, type, mask);
174 	up_read(&crypto_alg_sem);
175 
176 	return alg;
177 }
178 
179 struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
180 {
181 	struct crypto_alg *alg;
182 	struct crypto_alg *larval;
183 	int ok;
184 
185 	if (!name)
186 		return ERR_PTR(-ENOENT);
187 
188 	mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
189 	type &= mask;
190 
191 	alg = try_then_request_module(crypto_alg_lookup(name, type, mask),
192 				      name);
193 	if (alg)
194 		return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
195 
196 	larval = crypto_larval_alloc(name, type, mask);
197 	if (IS_ERR(larval) || !crypto_is_larval(larval))
198 		return larval;
199 
200 	ok = crypto_notify(CRYPTO_MSG_ALG_REQUEST, larval);
201 	if (ok == NOTIFY_DONE) {
202 		request_module("cryptomgr");
203 		ok = crypto_notify(CRYPTO_MSG_ALG_REQUEST, larval);
204 	}
205 
206 	if (ok == NOTIFY_STOP)
207 		alg = crypto_larval_wait(larval);
208 	else {
209 		crypto_mod_put(larval);
210 		alg = ERR_PTR(-ENOENT);
211 	}
212 	crypto_larval_kill(larval);
213 	return alg;
214 }
215 EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
216 
217 static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
218 {
219 	const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
220 
221 	if (type_obj)
222 		return type_obj->init(tfm, type, mask);
223 
224 	switch (crypto_tfm_alg_type(tfm)) {
225 	case CRYPTO_ALG_TYPE_CIPHER:
226 		return crypto_init_cipher_ops(tfm);
227 
228 	case CRYPTO_ALG_TYPE_DIGEST:
229 		return crypto_init_digest_ops(tfm);
230 
231 	case CRYPTO_ALG_TYPE_COMPRESS:
232 		return crypto_init_compress_ops(tfm);
233 
234 	default:
235 		break;
236 	}
237 
238 	BUG();
239 	return -EINVAL;
240 }
241 
242 static void crypto_exit_ops(struct crypto_tfm *tfm)
243 {
244 	const struct crypto_type *type = tfm->__crt_alg->cra_type;
245 
246 	if (type) {
247 		if (type->exit)
248 			type->exit(tfm);
249 		return;
250 	}
251 
252 	switch (crypto_tfm_alg_type(tfm)) {
253 	case CRYPTO_ALG_TYPE_CIPHER:
254 		crypto_exit_cipher_ops(tfm);
255 		break;
256 
257 	case CRYPTO_ALG_TYPE_DIGEST:
258 		crypto_exit_digest_ops(tfm);
259 		break;
260 
261 	case CRYPTO_ALG_TYPE_COMPRESS:
262 		crypto_exit_compress_ops(tfm);
263 		break;
264 
265 	default:
266 		BUG();
267 
268 	}
269 }
270 
271 static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
272 {
273 	const struct crypto_type *type_obj = alg->cra_type;
274 	unsigned int len;
275 
276 	len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
277 	if (type_obj)
278 		return len + type_obj->ctxsize(alg, type, mask);
279 
280 	switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
281 	default:
282 		BUG();
283 
284 	case CRYPTO_ALG_TYPE_CIPHER:
285 		len += crypto_cipher_ctxsize(alg);
286 		break;
287 
288 	case CRYPTO_ALG_TYPE_DIGEST:
289 		len += crypto_digest_ctxsize(alg);
290 		break;
291 
292 	case CRYPTO_ALG_TYPE_COMPRESS:
293 		len += crypto_compress_ctxsize(alg);
294 		break;
295 	}
296 
297 	return len;
298 }
299 
300 void crypto_shoot_alg(struct crypto_alg *alg)
301 {
302 	down_write(&crypto_alg_sem);
303 	alg->cra_flags |= CRYPTO_ALG_DYING;
304 	up_write(&crypto_alg_sem);
305 }
306 EXPORT_SYMBOL_GPL(crypto_shoot_alg);
307 
308 struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
309 				      u32 mask)
310 {
311 	struct crypto_tfm *tfm = NULL;
312 	unsigned int tfm_size;
313 	int err = -ENOMEM;
314 
315 	tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
316 	tfm = kzalloc(tfm_size, GFP_KERNEL);
317 	if (tfm == NULL)
318 		goto out_err;
319 
320 	tfm->__crt_alg = alg;
321 
322 	err = crypto_init_ops(tfm, type, mask);
323 	if (err)
324 		goto out_free_tfm;
325 
326 	if (alg->cra_init && (err = alg->cra_init(tfm))) {
327 		if (err == -EAGAIN)
328 			crypto_shoot_alg(alg);
329 		goto cra_init_failed;
330 	}
331 
332 	goto out;
333 
334 cra_init_failed:
335 	crypto_exit_ops(tfm);
336 out_free_tfm:
337 	kfree(tfm);
338 out_err:
339 	tfm = ERR_PTR(err);
340 out:
341 	return tfm;
342 }
343 EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
344 
345 /*
346  *	crypto_alloc_base - Locate algorithm and allocate transform
347  *	@alg_name: Name of algorithm
348  *	@type: Type of algorithm
349  *	@mask: Mask for type comparison
350  *
351  *	crypto_alloc_base() will first attempt to locate an already loaded
352  *	algorithm.  If that fails and the kernel supports dynamically loadable
353  *	modules, it will then attempt to load a module of the same name or
354  *	alias.  If that fails it will send a query to any loaded crypto manager
355  *	to construct an algorithm on the fly.  A refcount is grabbed on the
356  *	algorithm which is then associated with the new transform.
357  *
358  *	The returned transform is of a non-determinate type.  Most people
359  *	should use one of the more specific allocation functions such as
360  *	crypto_alloc_blkcipher.
361  *
362  *	In case of error the return value is an error pointer.
363  */
364 struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
365 {
366 	struct crypto_tfm *tfm;
367 	int err;
368 
369 	for (;;) {
370 		struct crypto_alg *alg;
371 
372 		alg = crypto_alg_mod_lookup(alg_name, type, mask);
373 		if (IS_ERR(alg)) {
374 			err = PTR_ERR(alg);
375 			goto err;
376 		}
377 
378 		tfm = __crypto_alloc_tfm(alg, type, mask);
379 		if (!IS_ERR(tfm))
380 			return tfm;
381 
382 		crypto_mod_put(alg);
383 		err = PTR_ERR(tfm);
384 
385 err:
386 		if (err != -EAGAIN)
387 			break;
388 		if (signal_pending(current)) {
389 			err = -EINTR;
390 			break;
391 		}
392 	}
393 
394 	return ERR_PTR(err);
395 }
396 EXPORT_SYMBOL_GPL(crypto_alloc_base);
397 
398 /*
399  *	crypto_free_tfm - Free crypto transform
400  *	@tfm: Transform to free
401  *
402  *	crypto_free_tfm() frees up the transform and any associated resources,
403  *	then drops the refcount on the associated algorithm.
404  */
405 void crypto_free_tfm(struct crypto_tfm *tfm)
406 {
407 	struct crypto_alg *alg;
408 	int size;
409 
410 	if (unlikely(!tfm))
411 		return;
412 
413 	alg = tfm->__crt_alg;
414 	size = sizeof(*tfm) + alg->cra_ctxsize;
415 
416 	if (alg->cra_exit)
417 		alg->cra_exit(tfm);
418 	crypto_exit_ops(tfm);
419 	crypto_mod_put(alg);
420 	memset(tfm, 0, size);
421 	kfree(tfm);
422 }
423 
424 EXPORT_SYMBOL_GPL(crypto_free_tfm);
425 
426 int crypto_has_alg(const char *name, u32 type, u32 mask)
427 {
428 	int ret = 0;
429 	struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
430 
431 	if (!IS_ERR(alg)) {
432 		crypto_mod_put(alg);
433 		ret = 1;
434 	}
435 
436 	return ret;
437 }
438 EXPORT_SYMBOL_GPL(crypto_has_alg);
439