xref: /linux/crypto/api.c (revision 6396bb221514d2876fd6dc0aa2a1f240d99b37bb) 
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  	refcount_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  static struct crypto_alg *crypto_alg_lookup(const char *name, u32 type,
197  					    u32 mask)
198  {
199  	struct crypto_alg *alg;
200  	u32 test = 0;
201  
202  	if (!((type | mask) & CRYPTO_ALG_TESTED))
203  		test |= CRYPTO_ALG_TESTED;
204  
205  	down_read(&crypto_alg_sem);
206  	alg = __crypto_alg_lookup(name, type | test, mask | test);
207  	if (!alg && test) {
208  		alg = __crypto_alg_lookup(name, type, mask);
209  		if (alg && !crypto_is_larval(alg)) {
210  			/* Test failed */
211  			crypto_mod_put(alg);
212  			alg = ERR_PTR(-ELIBBAD);
213  		}
214  	}
215  	up_read(&crypto_alg_sem);
216  
217  	return alg;
218  }
219  
220  static struct crypto_alg *crypto_larval_lookup(const char *name, u32 type,
221  					       u32 mask)
222  {
223  	struct crypto_alg *alg;
224  
225  	if (!name)
226  		return ERR_PTR(-ENOENT);
227  
228  	type &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
229  	mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
230  
231  	alg = crypto_alg_lookup(name, type, mask);
232  	if (!alg) {
233  		request_module("crypto-%s", name);
234  
235  		if (!((type ^ CRYPTO_ALG_NEED_FALLBACK) & mask &
236  		      CRYPTO_ALG_NEED_FALLBACK))
237  			request_module("crypto-%s-all", name);
238  
239  		alg = crypto_alg_lookup(name, type, mask);
240  	}
241  
242  	if (!IS_ERR_OR_NULL(alg) && crypto_is_larval(alg))
243  		alg = crypto_larval_wait(alg);
244  	else if (!alg)
245  		alg = crypto_larval_add(name, type, mask);
246  
247  	return alg;
248  }
249  
250  int crypto_probing_notify(unsigned long val, void *v)
251  {
252  	int ok;
253  
254  	ok = blocking_notifier_call_chain(&crypto_chain, val, v);
255  	if (ok == NOTIFY_DONE) {
256  		request_module("cryptomgr");
257  		ok = blocking_notifier_call_chain(&crypto_chain, val, v);
258  	}
259  
260  	return ok;
261  }
262  EXPORT_SYMBOL_GPL(crypto_probing_notify);
263  
264  struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
265  {
266  	struct crypto_alg *alg;
267  	struct crypto_alg *larval;
268  	int ok;
269  
270  	/*
271  	 * If the internal flag is set for a cipher, require a caller to
272  	 * to invoke the cipher with the internal flag to use that cipher.
273  	 * Also, if a caller wants to allocate a cipher that may or may
274  	 * not be an internal cipher, use type | CRYPTO_ALG_INTERNAL and
275  	 * !(mask & CRYPTO_ALG_INTERNAL).
276  	 */
277  	if (!((type | mask) & CRYPTO_ALG_INTERNAL))
278  		mask |= CRYPTO_ALG_INTERNAL;
279  
280  	larval = crypto_larval_lookup(name, type, mask);
281  	if (IS_ERR(larval) || !crypto_is_larval(larval))
282  		return larval;
283  
284  	ok = crypto_probing_notify(CRYPTO_MSG_ALG_REQUEST, larval);
285  
286  	if (ok == NOTIFY_STOP)
287  		alg = crypto_larval_wait(larval);
288  	else {
289  		crypto_mod_put(larval);
290  		alg = ERR_PTR(-ENOENT);
291  	}
292  	crypto_larval_kill(larval);
293  	return alg;
294  }
295  EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
296  
297  static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
298  {
299  	const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
300  
301  	if (type_obj)
302  		return type_obj->init(tfm, type, mask);
303  
304  	switch (crypto_tfm_alg_type(tfm)) {
305  	case CRYPTO_ALG_TYPE_CIPHER:
306  		return crypto_init_cipher_ops(tfm);
307  
308  	case CRYPTO_ALG_TYPE_COMPRESS:
309  		return crypto_init_compress_ops(tfm);
310  
311  	default:
312  		break;
313  	}
314  
315  	BUG();
316  	return -EINVAL;
317  }
318  
319  static void crypto_exit_ops(struct crypto_tfm *tfm)
320  {
321  	const struct crypto_type *type = tfm->__crt_alg->cra_type;
322  
323  	if (type && tfm->exit)
324  		tfm->exit(tfm);
325  }
326  
327  static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
328  {
329  	const struct crypto_type *type_obj = alg->cra_type;
330  	unsigned int len;
331  
332  	len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
333  	if (type_obj)
334  		return len + type_obj->ctxsize(alg, type, mask);
335  
336  	switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
337  	default:
338  		BUG();
339  
340  	case CRYPTO_ALG_TYPE_CIPHER:
341  		len += crypto_cipher_ctxsize(alg);
342  		break;
343  
344  	case CRYPTO_ALG_TYPE_COMPRESS:
345  		len += crypto_compress_ctxsize(alg);
346  		break;
347  	}
348  
349  	return len;
350  }
351  
352  void crypto_shoot_alg(struct crypto_alg *alg)
353  {
354  	down_write(&crypto_alg_sem);
355  	alg->cra_flags |= CRYPTO_ALG_DYING;
356  	up_write(&crypto_alg_sem);
357  }
358  EXPORT_SYMBOL_GPL(crypto_shoot_alg);
359  
360  struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
361  				      u32 mask)
362  {
363  	struct crypto_tfm *tfm = NULL;
364  	unsigned int tfm_size;
365  	int err = -ENOMEM;
366  
367  	tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
368  	tfm = kzalloc(tfm_size, GFP_KERNEL);
369  	if (tfm == NULL)
370  		goto out_err;
371  
372  	tfm->__crt_alg = alg;
373  
374  	err = crypto_init_ops(tfm, type, mask);
375  	if (err)
376  		goto out_free_tfm;
377  
378  	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
379  		goto cra_init_failed;
380  
381  	goto out;
382  
383  cra_init_failed:
384  	crypto_exit_ops(tfm);
385  out_free_tfm:
386  	if (err == -EAGAIN)
387  		crypto_shoot_alg(alg);
388  	kfree(tfm);
389  out_err:
390  	tfm = ERR_PTR(err);
391  out:
392  	return tfm;
393  }
394  EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
395  
396  /*
397   *	crypto_alloc_base - Locate algorithm and allocate transform
398   *	@alg_name: Name of algorithm
399   *	@type: Type of algorithm
400   *	@mask: Mask for type comparison
401   *
402   *	This function should not be used by new algorithm types.
403   *	Please use crypto_alloc_tfm instead.
404   *
405   *	crypto_alloc_base() will first attempt to locate an already loaded
406   *	algorithm.  If that fails and the kernel supports dynamically loadable
407   *	modules, it will then attempt to load a module of the same name or
408   *	alias.  If that fails it will send a query to any loaded crypto manager
409   *	to construct an algorithm on the fly.  A refcount is grabbed on the
410   *	algorithm which is then associated with the new transform.
411   *
412   *	The returned transform is of a non-determinate type.  Most people
413   *	should use one of the more specific allocation functions such as
414   *	crypto_alloc_blkcipher.
415   *
416   *	In case of error the return value is an error pointer.
417   */
418  struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
419  {
420  	struct crypto_tfm *tfm;
421  	int err;
422  
423  	for (;;) {
424  		struct crypto_alg *alg;
425  
426  		alg = crypto_alg_mod_lookup(alg_name, type, mask);
427  		if (IS_ERR(alg)) {
428  			err = PTR_ERR(alg);
429  			goto err;
430  		}
431  
432  		tfm = __crypto_alloc_tfm(alg, type, mask);
433  		if (!IS_ERR(tfm))
434  			return tfm;
435  
436  		crypto_mod_put(alg);
437  		err = PTR_ERR(tfm);
438  
439  err:
440  		if (err != -EAGAIN)
441  			break;
442  		if (fatal_signal_pending(current)) {
443  			err = -EINTR;
444  			break;
445  		}
446  	}
447  
448  	return ERR_PTR(err);
449  }
450  EXPORT_SYMBOL_GPL(crypto_alloc_base);
451  
452  void *crypto_create_tfm(struct crypto_alg *alg,
453  			const struct crypto_type *frontend)
454  {
455  	char *mem;
456  	struct crypto_tfm *tfm = NULL;
457  	unsigned int tfmsize;
458  	unsigned int total;
459  	int err = -ENOMEM;
460  
461  	tfmsize = frontend->tfmsize;
462  	total = tfmsize + sizeof(*tfm) + frontend->extsize(alg);
463  
464  	mem = kzalloc(total, GFP_KERNEL);
465  	if (mem == NULL)
466  		goto out_err;
467  
468  	tfm = (struct crypto_tfm *)(mem + tfmsize);
469  	tfm->__crt_alg = alg;
470  
471  	err = frontend->init_tfm(tfm);
472  	if (err)
473  		goto out_free_tfm;
474  
475  	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
476  		goto cra_init_failed;
477  
478  	goto out;
479  
480  cra_init_failed:
481  	crypto_exit_ops(tfm);
482  out_free_tfm:
483  	if (err == -EAGAIN)
484  		crypto_shoot_alg(alg);
485  	kfree(mem);
486  out_err:
487  	mem = ERR_PTR(err);
488  out:
489  	return mem;
490  }
491  EXPORT_SYMBOL_GPL(crypto_create_tfm);
492  
493  struct crypto_alg *crypto_find_alg(const char *alg_name,
494  				   const struct crypto_type *frontend,
495  				   u32 type, u32 mask)
496  {
497  	if (frontend) {
498  		type &= frontend->maskclear;
499  		mask &= frontend->maskclear;
500  		type |= frontend->type;
501  		mask |= frontend->maskset;
502  	}
503  
504  	return crypto_alg_mod_lookup(alg_name, type, mask);
505  }
506  EXPORT_SYMBOL_GPL(crypto_find_alg);
507  
508  /*
509   *	crypto_alloc_tfm - Locate algorithm and allocate transform
510   *	@alg_name: Name of algorithm
511   *	@frontend: Frontend algorithm type
512   *	@type: Type of algorithm
513   *	@mask: Mask for type comparison
514   *
515   *	crypto_alloc_tfm() will first attempt to locate an already loaded
516   *	algorithm.  If that fails and the kernel supports dynamically loadable
517   *	modules, it will then attempt to load a module of the same name or
518   *	alias.  If that fails it will send a query to any loaded crypto manager
519   *	to construct an algorithm on the fly.  A refcount is grabbed on the
520   *	algorithm which is then associated with the new transform.
521   *
522   *	The returned transform is of a non-determinate type.  Most people
523   *	should use one of the more specific allocation functions such as
524   *	crypto_alloc_blkcipher.
525   *
526   *	In case of error the return value is an error pointer.
527   */
528  void *crypto_alloc_tfm(const char *alg_name,
529  		       const struct crypto_type *frontend, u32 type, u32 mask)
530  {
531  	void *tfm;
532  	int err;
533  
534  	for (;;) {
535  		struct crypto_alg *alg;
536  
537  		alg = crypto_find_alg(alg_name, frontend, type, mask);
538  		if (IS_ERR(alg)) {
539  			err = PTR_ERR(alg);
540  			goto err;
541  		}
542  
543  		tfm = crypto_create_tfm(alg, frontend);
544  		if (!IS_ERR(tfm))
545  			return tfm;
546  
547  		crypto_mod_put(alg);
548  		err = PTR_ERR(tfm);
549  
550  err:
551  		if (err != -EAGAIN)
552  			break;
553  		if (fatal_signal_pending(current)) {
554  			err = -EINTR;
555  			break;
556  		}
557  	}
558  
559  	return ERR_PTR(err);
560  }
561  EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
562  
563  /*
564   *	crypto_destroy_tfm - Free crypto transform
565   *	@mem: Start of tfm slab
566   *	@tfm: Transform to free
567   *
568   *	This function frees up the transform and any associated resources,
569   *	then drops the refcount on the associated algorithm.
570   */
571  void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
572  {
573  	struct crypto_alg *alg;
574  
575  	if (unlikely(!mem))
576  		return;
577  
578  	alg = tfm->__crt_alg;
579  
580  	if (!tfm->exit && alg->cra_exit)
581  		alg->cra_exit(tfm);
582  	crypto_exit_ops(tfm);
583  	crypto_mod_put(alg);
584  	kzfree(mem);
585  }
586  EXPORT_SYMBOL_GPL(crypto_destroy_tfm);
587  
588  int crypto_has_alg(const char *name, u32 type, u32 mask)
589  {
590  	int ret = 0;
591  	struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
592  
593  	if (!IS_ERR(alg)) {
594  		crypto_mod_put(alg);
595  		ret = 1;
596  	}
597  
598  	return ret;
599  }
600  EXPORT_SYMBOL_GPL(crypto_has_alg);
601  
602  void crypto_req_done(struct crypto_async_request *req, int err)
603  {
604  	struct crypto_wait *wait = req->data;
605  
606  	if (err == -EINPROGRESS)
607  		return;
608  
609  	wait->err = err;
610  	complete(&wait->completion);
611  }
612  EXPORT_SYMBOL_GPL(crypto_req_done);
613  
614  MODULE_DESCRIPTION("Cryptographic core API");
615  MODULE_LICENSE("GPL");
616