Root/crypto/api.c

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
29LIST_HEAD(crypto_alg_list);
30EXPORT_SYMBOL_GPL(crypto_alg_list);
31DECLARE_RWSEM(crypto_alg_sem);
32EXPORT_SYMBOL_GPL(crypto_alg_sem);
33
34BLOCKING_NOTIFIER_HEAD(crypto_chain);
35EXPORT_SYMBOL_GPL(crypto_chain);
36
37static inline struct crypto_alg *crypto_alg_get(struct crypto_alg *alg)
38{
39    atomic_inc(&alg->cra_refcnt);
40    return alg;
41}
42
43struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)
44{
45    return try_module_get(alg->cra_module) ? crypto_alg_get(alg) : NULL;
46}
47EXPORT_SYMBOL_GPL(crypto_mod_get);
48
49void 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}
56EXPORT_SYMBOL_GPL(crypto_mod_put);
57
58static inline int crypto_is_test_larval(struct crypto_larval *larval)
59{
60    return larval->alg.cra_driver_name[0];
61}
62
63static struct crypto_alg *__crypto_alg_lookup(const char *name, u32 type,
64                          u32 mask)
65{
66    struct crypto_alg *q, *alg = NULL;
67    int best = -2;
68
69    list_for_each_entry(q, &crypto_alg_list, cra_list) {
70        int exact, fuzzy;
71
72        if (crypto_is_moribund(q))
73            continue;
74
75        if ((q->cra_flags ^ type) & mask)
76            continue;
77
78        if (crypto_is_larval(q) &&
79            !crypto_is_test_larval((struct crypto_larval *)q) &&
80            ((struct crypto_larval *)q)->mask != mask)
81            continue;
82
83        exact = !strcmp(q->cra_driver_name, name);
84        fuzzy = !strcmp(q->cra_name, name);
85        if (!exact && !(fuzzy && q->cra_priority > best))
86            continue;
87
88        if (unlikely(!crypto_mod_get(q)))
89            continue;
90
91        best = q->cra_priority;
92        if (alg)
93            crypto_mod_put(alg);
94        alg = q;
95
96        if (exact)
97            break;
98    }
99
100    return alg;
101}
102
103static void crypto_larval_destroy(struct crypto_alg *alg)
104{
105    struct crypto_larval *larval = (void *)alg;
106
107    BUG_ON(!crypto_is_larval(alg));
108    if (larval->adult)
109        crypto_mod_put(larval->adult);
110    kfree(larval);
111}
112
113struct crypto_larval *crypto_larval_alloc(const char *name, u32 type, u32 mask)
114{
115    struct crypto_larval *larval;
116
117    larval = kzalloc(sizeof(*larval), GFP_KERNEL);
118    if (!larval)
119        return ERR_PTR(-ENOMEM);
120
121    larval->mask = mask;
122    larval->alg.cra_flags = CRYPTO_ALG_LARVAL | type;
123    larval->alg.cra_priority = -1;
124    larval->alg.cra_destroy = crypto_larval_destroy;
125
126    strlcpy(larval->alg.cra_name, name, CRYPTO_MAX_ALG_NAME);
127    init_completion(&larval->completion);
128
129    return larval;
130}
131EXPORT_SYMBOL_GPL(crypto_larval_alloc);
132
133static struct crypto_alg *crypto_larval_add(const char *name, u32 type,
134                        u32 mask)
135{
136    struct crypto_alg *alg;
137    struct crypto_larval *larval;
138
139    larval = crypto_larval_alloc(name, type, mask);
140    if (IS_ERR(larval))
141        return ERR_CAST(larval);
142
143    atomic_set(&larval->alg.cra_refcnt, 2);
144
145    down_write(&crypto_alg_sem);
146    alg = __crypto_alg_lookup(name, type, mask);
147    if (!alg) {
148        alg = &larval->alg;
149        list_add(&alg->cra_list, &crypto_alg_list);
150    }
151    up_write(&crypto_alg_sem);
152
153    if (alg != &larval->alg)
154        kfree(larval);
155
156    return alg;
157}
158
159void 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}
169EXPORT_SYMBOL_GPL(crypto_larval_kill);
170
171static 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_interruptible_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
196struct 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}
206EXPORT_SYMBOL_GPL(crypto_alg_lookup);
207
208struct 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    mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
216    type &= mask;
217
218    alg = crypto_alg_lookup(name, type, mask);
219    if (!alg) {
220        request_module("%s", name);
221
222        if (!((type ^ CRYPTO_ALG_NEED_FALLBACK) & mask &
223              CRYPTO_ALG_NEED_FALLBACK))
224            request_module("%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}
234EXPORT_SYMBOL_GPL(crypto_larval_lookup);
235
236int 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}
248EXPORT_SYMBOL_GPL(crypto_probing_notify);
249
250struct 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    larval = crypto_larval_lookup(name, type, mask);
262    if (IS_ERR(larval) || !crypto_is_larval(larval))
263        return larval;
264
265    ok = crypto_probing_notify(CRYPTO_MSG_ALG_REQUEST, larval);
266
267    if (ok == NOTIFY_STOP)
268        alg = crypto_larval_wait(larval);
269    else {
270        crypto_mod_put(larval);
271        alg = ERR_PTR(-ENOENT);
272    }
273    crypto_larval_kill(larval);
274    return alg;
275}
276EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
277
278static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
279{
280    const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
281
282    if (type_obj)
283        return type_obj->init(tfm, type, mask);
284
285    switch (crypto_tfm_alg_type(tfm)) {
286    case CRYPTO_ALG_TYPE_CIPHER:
287        return crypto_init_cipher_ops(tfm);
288
289    case CRYPTO_ALG_TYPE_COMPRESS:
290        return crypto_init_compress_ops(tfm);
291
292    default:
293        break;
294    }
295
296    BUG();
297    return -EINVAL;
298}
299
300static void crypto_exit_ops(struct crypto_tfm *tfm)
301{
302    const struct crypto_type *type = tfm->__crt_alg->cra_type;
303
304    if (type) {
305        if (tfm->exit)
306            tfm->exit(tfm);
307        return;
308    }
309
310    switch (crypto_tfm_alg_type(tfm)) {
311    case CRYPTO_ALG_TYPE_CIPHER:
312        crypto_exit_cipher_ops(tfm);
313        break;
314
315    case CRYPTO_ALG_TYPE_COMPRESS:
316        crypto_exit_compress_ops(tfm);
317        break;
318
319    default:
320        BUG();
321    }
322}
323
324static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
325{
326    const struct crypto_type *type_obj = alg->cra_type;
327    unsigned int len;
328
329    len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
330    if (type_obj)
331        return len + type_obj->ctxsize(alg, type, mask);
332
333    switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
334    default:
335        BUG();
336
337    case CRYPTO_ALG_TYPE_CIPHER:
338        len += crypto_cipher_ctxsize(alg);
339        break;
340
341    case CRYPTO_ALG_TYPE_COMPRESS:
342        len += crypto_compress_ctxsize(alg);
343        break;
344    }
345
346    return len;
347}
348
349void crypto_shoot_alg(struct crypto_alg *alg)
350{
351    down_write(&crypto_alg_sem);
352    alg->cra_flags |= CRYPTO_ALG_DYING;
353    up_write(&crypto_alg_sem);
354}
355EXPORT_SYMBOL_GPL(crypto_shoot_alg);
356
357struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
358                      u32 mask)
359{
360    struct crypto_tfm *tfm = NULL;
361    unsigned int tfm_size;
362    int err = -ENOMEM;
363
364    tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
365    tfm = kzalloc(tfm_size, GFP_KERNEL);
366    if (tfm == NULL)
367        goto out_err;
368
369    tfm->__crt_alg = alg;
370
371    err = crypto_init_ops(tfm, type, mask);
372    if (err)
373        goto out_free_tfm;
374
375    if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
376        goto cra_init_failed;
377
378    goto out;
379
380cra_init_failed:
381    crypto_exit_ops(tfm);
382out_free_tfm:
383    if (err == -EAGAIN)
384        crypto_shoot_alg(alg);
385    kfree(tfm);
386out_err:
387    tfm = ERR_PTR(err);
388out:
389    return tfm;
390}
391EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
392
393/*
394 * crypto_alloc_base - Locate algorithm and allocate transform
395 * @alg_name: Name of algorithm
396 * @type: Type of algorithm
397 * @mask: Mask for type comparison
398 *
399 * This function should not be used by new algorithm types.
400 * Plesae use crypto_alloc_tfm instead.
401 *
402 * crypto_alloc_base() will first attempt to locate an already loaded
403 * algorithm. If that fails and the kernel supports dynamically loadable
404 * modules, it will then attempt to load a module of the same name or
405 * alias. If that fails it will send a query to any loaded crypto manager
406 * to construct an algorithm on the fly. A refcount is grabbed on the
407 * algorithm which is then associated with the new transform.
408 *
409 * The returned transform is of a non-determinate type. Most people
410 * should use one of the more specific allocation functions such as
411 * crypto_alloc_blkcipher.
412 *
413 * In case of error the return value is an error pointer.
414 */
415struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
416{
417    struct crypto_tfm *tfm;
418    int err;
419
420    for (;;) {
421        struct crypto_alg *alg;
422
423        alg = crypto_alg_mod_lookup(alg_name, type, mask);
424        if (IS_ERR(alg)) {
425            err = PTR_ERR(alg);
426            goto err;
427        }
428
429        tfm = __crypto_alloc_tfm(alg, type, mask);
430        if (!IS_ERR(tfm))
431            return tfm;
432
433        crypto_mod_put(alg);
434        err = PTR_ERR(tfm);
435
436err:
437        if (err != -EAGAIN)
438            break;
439        if (signal_pending(current)) {
440            err = -EINTR;
441            break;
442        }
443    }
444
445    return ERR_PTR(err);
446}
447EXPORT_SYMBOL_GPL(crypto_alloc_base);
448
449void *crypto_create_tfm(struct crypto_alg *alg,
450            const struct crypto_type *frontend)
451{
452    char *mem;
453    struct crypto_tfm *tfm = NULL;
454    unsigned int tfmsize;
455    unsigned int total;
456    int err = -ENOMEM;
457
458    tfmsize = frontend->tfmsize;
459    total = tfmsize + sizeof(*tfm) + frontend->extsize(alg);
460
461    mem = kzalloc(total, GFP_KERNEL);
462    if (mem == NULL)
463        goto out_err;
464
465    tfm = (struct crypto_tfm *)(mem + tfmsize);
466    tfm->__crt_alg = alg;
467
468    err = frontend->init_tfm(tfm);
469    if (err)
470        goto out_free_tfm;
471
472    if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
473        goto cra_init_failed;
474
475    goto out;
476
477cra_init_failed:
478    crypto_exit_ops(tfm);
479out_free_tfm:
480    if (err == -EAGAIN)
481        crypto_shoot_alg(alg);
482    kfree(mem);
483out_err:
484    mem = ERR_PTR(err);
485out:
486    return mem;
487}
488EXPORT_SYMBOL_GPL(crypto_create_tfm);
489
490struct crypto_alg *crypto_find_alg(const char *alg_name,
491                   const struct crypto_type *frontend,
492                   u32 type, u32 mask)
493{
494    struct crypto_alg *(*lookup)(const char *name, u32 type, u32 mask) =
495        crypto_alg_mod_lookup;
496
497    if (frontend) {
498        type &= frontend->maskclear;
499        mask &= frontend->maskclear;
500        type |= frontend->type;
501        mask |= frontend->maskset;
502
503        if (frontend->lookup)
504            lookup = frontend->lookup;
505    }
506
507    return lookup(alg_name, type, mask);
508}
509EXPORT_SYMBOL_GPL(crypto_find_alg);
510
511/*
512 * crypto_alloc_tfm - Locate algorithm and allocate transform
513 * @alg_name: Name of algorithm
514 * @frontend: Frontend algorithm type
515 * @type: Type of algorithm
516 * @mask: Mask for type comparison
517 *
518 * crypto_alloc_tfm() will first attempt to locate an already loaded
519 * algorithm. If that fails and the kernel supports dynamically loadable
520 * modules, it will then attempt to load a module of the same name or
521 * alias. If that fails it will send a query to any loaded crypto manager
522 * to construct an algorithm on the fly. A refcount is grabbed on the
523 * algorithm which is then associated with the new transform.
524 *
525 * The returned transform is of a non-determinate type. Most people
526 * should use one of the more specific allocation functions such as
527 * crypto_alloc_blkcipher.
528 *
529 * In case of error the return value is an error pointer.
530 */
531void *crypto_alloc_tfm(const char *alg_name,
532               const struct crypto_type *frontend, u32 type, u32 mask)
533{
534    void *tfm;
535    int err;
536
537    for (;;) {
538        struct crypto_alg *alg;
539
540        alg = crypto_find_alg(alg_name, frontend, type, mask);
541        if (IS_ERR(alg)) {
542            err = PTR_ERR(alg);
543            goto err;
544        }
545
546        tfm = crypto_create_tfm(alg, frontend);
547        if (!IS_ERR(tfm))
548            return tfm;
549
550        crypto_mod_put(alg);
551        err = PTR_ERR(tfm);
552
553err:
554        if (err != -EAGAIN)
555            break;
556        if (signal_pending(current)) {
557            err = -EINTR;
558            break;
559        }
560    }
561
562    return ERR_PTR(err);
563}
564EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
565
566/*
567 * crypto_destroy_tfm - Free crypto transform
568 * @mem: Start of tfm slab
569 * @tfm: Transform to free
570 *
571 * This function frees up the transform and any associated resources,
572 * then drops the refcount on the associated algorithm.
573 */
574void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
575{
576    struct crypto_alg *alg;
577
578    if (unlikely(!mem))
579        return;
580
581    alg = tfm->__crt_alg;
582
583    if (!tfm->exit && alg->cra_exit)
584        alg->cra_exit(tfm);
585    crypto_exit_ops(tfm);
586    crypto_mod_put(alg);
587    kzfree(mem);
588}
589EXPORT_SYMBOL_GPL(crypto_destroy_tfm);
590
591int crypto_has_alg(const char *name, u32 type, u32 mask)
592{
593    int ret = 0;
594    struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
595
596    if (!IS_ERR(alg)) {
597        crypto_mod_put(alg);
598        ret = 1;
599    }
600
601    return ret;
602}
603EXPORT_SYMBOL_GPL(crypto_has_alg);
604
605MODULE_DESCRIPTION("Cryptographic core API");
606MODULE_LICENSE("GPL");
607

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