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 struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg);
38
39struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)
40{
41    return try_module_get(alg->cra_module) ? crypto_alg_get(alg) : NULL;
42}
43EXPORT_SYMBOL_GPL(crypto_mod_get);
44
45void crypto_mod_put(struct crypto_alg *alg)
46{
47    struct module *module = alg->cra_module;
48
49    crypto_alg_put(alg);
50    module_put(module);
51}
52EXPORT_SYMBOL_GPL(crypto_mod_put);
53
54static inline int crypto_is_test_larval(struct crypto_larval *larval)
55{
56    return larval->alg.cra_driver_name[0];
57}
58
59static struct crypto_alg *__crypto_alg_lookup(const char *name, u32 type,
60                          u32 mask)
61{
62    struct crypto_alg *q, *alg = NULL;
63    int best = -2;
64
65    list_for_each_entry(q, &crypto_alg_list, cra_list) {
66        int exact, fuzzy;
67
68        if (crypto_is_moribund(q))
69            continue;
70
71        if ((q->cra_flags ^ type) & mask)
72            continue;
73
74        if (crypto_is_larval(q) &&
75            !crypto_is_test_larval((struct crypto_larval *)q) &&
76            ((struct crypto_larval *)q)->mask != mask)
77            continue;
78
79        exact = !strcmp(q->cra_driver_name, name);
80        fuzzy = !strcmp(q->cra_name, name);
81        if (!exact && !(fuzzy && q->cra_priority > best))
82            continue;
83
84        if (unlikely(!crypto_mod_get(q)))
85            continue;
86
87        best = q->cra_priority;
88        if (alg)
89            crypto_mod_put(alg);
90        alg = q;
91
92        if (exact)
93            break;
94    }
95
96    return alg;
97}
98
99static void crypto_larval_destroy(struct crypto_alg *alg)
100{
101    struct crypto_larval *larval = (void *)alg;
102
103    BUG_ON(!crypto_is_larval(alg));
104    if (larval->adult)
105        crypto_mod_put(larval->adult);
106    kfree(larval);
107}
108
109struct crypto_larval *crypto_larval_alloc(const char *name, u32 type, u32 mask)
110{
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    strlcpy(larval->alg.cra_name, name, CRYPTO_MAX_ALG_NAME);
123    init_completion(&larval->completion);
124
125    return larval;
126}
127EXPORT_SYMBOL_GPL(crypto_larval_alloc);
128
129static struct crypto_alg *crypto_larval_add(const char *name, u32 type,
130                        u32 mask)
131{
132    struct crypto_alg *alg;
133    struct crypto_larval *larval;
134
135    larval = crypto_larval_alloc(name, type, mask);
136    if (IS_ERR(larval))
137        return ERR_CAST(larval);
138
139    atomic_set(&larval->alg.cra_refcnt, 2);
140
141    down_write(&crypto_alg_sem);
142    alg = __crypto_alg_lookup(name, type, mask);
143    if (!alg) {
144        alg = &larval->alg;
145        list_add(&alg->cra_list, &crypto_alg_list);
146    }
147    up_write(&crypto_alg_sem);
148
149    if (alg != &larval->alg) {
150        kfree(larval);
151        if (crypto_is_larval(alg))
152            alg = crypto_larval_wait(alg);
153    }
154
155    return alg;
156}
157
158void crypto_larval_kill(struct crypto_alg *alg)
159{
160    struct crypto_larval *larval = (void *)alg;
161
162    down_write(&crypto_alg_sem);
163    list_del(&alg->cra_list);
164    up_write(&crypto_alg_sem);
165    complete_all(&larval->completion);
166    crypto_alg_put(alg);
167}
168EXPORT_SYMBOL_GPL(crypto_larval_kill);
169
170static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg)
171{
172    struct crypto_larval *larval = (void *)alg;
173    long timeout;
174
175    timeout = wait_for_completion_interruptible_timeout(
176        &larval->completion, 60 * HZ);
177
178    alg = larval->adult;
179    if (timeout < 0)
180        alg = ERR_PTR(-EINTR);
181    else if (!timeout)
182        alg = ERR_PTR(-ETIMEDOUT);
183    else if (!alg)
184        alg = ERR_PTR(-ENOENT);
185    else if (crypto_is_test_larval(larval) &&
186         !(alg->cra_flags & CRYPTO_ALG_TESTED))
187        alg = ERR_PTR(-EAGAIN);
188    else if (!crypto_mod_get(alg))
189        alg = ERR_PTR(-EAGAIN);
190    crypto_mod_put(&larval->alg);
191
192    return alg;
193}
194
195struct crypto_alg *crypto_alg_lookup(const char *name, u32 type, u32 mask)
196{
197    struct crypto_alg *alg;
198
199    down_read(&crypto_alg_sem);
200    alg = __crypto_alg_lookup(name, type, mask);
201    up_read(&crypto_alg_sem);
202
203    return alg;
204}
205EXPORT_SYMBOL_GPL(crypto_alg_lookup);
206
207struct crypto_alg *crypto_larval_lookup(const char *name, u32 type, u32 mask)
208{
209    struct crypto_alg *alg;
210
211    if (!name)
212        return ERR_PTR(-ENOENT);
213
214    mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
215    type &= mask;
216
217    alg = crypto_alg_lookup(name, type, mask);
218    if (!alg) {
219        request_module("%s", name);
220
221        if (!((type ^ CRYPTO_ALG_NEED_FALLBACK) & mask &
222              CRYPTO_ALG_NEED_FALLBACK))
223            request_module("%s-all", name);
224
225        alg = crypto_alg_lookup(name, type, mask);
226    }
227
228    if (alg)
229        return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
230
231    return crypto_larval_add(name, type, mask);
232}
233EXPORT_SYMBOL_GPL(crypto_larval_lookup);
234
235int crypto_probing_notify(unsigned long val, void *v)
236{
237    int ok;
238
239    ok = blocking_notifier_call_chain(&crypto_chain, val, v);
240    if (ok == NOTIFY_DONE) {
241        request_module("cryptomgr");
242        ok = blocking_notifier_call_chain(&crypto_chain, val, v);
243    }
244
245    return ok;
246}
247EXPORT_SYMBOL_GPL(crypto_probing_notify);
248
249struct crypto_alg *crypto_alg_mod_lookup(const char *name, u32 type, u32 mask)
250{
251    struct crypto_alg *alg;
252    struct crypto_alg *larval;
253    int ok;
254
255    if (!((type | mask) & CRYPTO_ALG_TESTED)) {
256        type |= CRYPTO_ALG_TESTED;
257        mask |= CRYPTO_ALG_TESTED;
258    }
259
260    larval = crypto_larval_lookup(name, type, mask);
261    if (IS_ERR(larval) || !crypto_is_larval(larval))
262        return larval;
263
264    ok = crypto_probing_notify(CRYPTO_MSG_ALG_REQUEST, larval);
265
266    if (ok == NOTIFY_STOP)
267        alg = crypto_larval_wait(larval);
268    else {
269        crypto_mod_put(larval);
270        alg = ERR_PTR(-ENOENT);
271    }
272    crypto_larval_kill(larval);
273    return alg;
274}
275EXPORT_SYMBOL_GPL(crypto_alg_mod_lookup);
276
277static int crypto_init_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
278{
279    const struct crypto_type *type_obj = tfm->__crt_alg->cra_type;
280
281    if (type_obj)
282        return type_obj->init(tfm, type, mask);
283
284    switch (crypto_tfm_alg_type(tfm)) {
285    case CRYPTO_ALG_TYPE_CIPHER:
286        return crypto_init_cipher_ops(tfm);
287
288    case CRYPTO_ALG_TYPE_COMPRESS:
289        return crypto_init_compress_ops(tfm);
290
291    default:
292        break;
293    }
294
295    BUG();
296    return -EINVAL;
297}
298
299static void crypto_exit_ops(struct crypto_tfm *tfm)
300{
301    const struct crypto_type *type = tfm->__crt_alg->cra_type;
302
303    if (type) {
304        if (tfm->exit)
305            tfm->exit(tfm);
306        return;
307    }
308
309    switch (crypto_tfm_alg_type(tfm)) {
310    case CRYPTO_ALG_TYPE_CIPHER:
311        crypto_exit_cipher_ops(tfm);
312        break;
313
314    case CRYPTO_ALG_TYPE_COMPRESS:
315        crypto_exit_compress_ops(tfm);
316        break;
317
318    default:
319        BUG();
320    }
321}
322
323static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
324{
325    const struct crypto_type *type_obj = alg->cra_type;
326    unsigned int len;
327
328    len = alg->cra_alignmask & ~(crypto_tfm_ctx_alignment() - 1);
329    if (type_obj)
330        return len + type_obj->ctxsize(alg, type, mask);
331
332    switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
333    default:
334        BUG();
335
336    case CRYPTO_ALG_TYPE_CIPHER:
337        len += crypto_cipher_ctxsize(alg);
338        break;
339
340    case CRYPTO_ALG_TYPE_COMPRESS:
341        len += crypto_compress_ctxsize(alg);
342        break;
343    }
344
345    return len;
346}
347
348void crypto_shoot_alg(struct crypto_alg *alg)
349{
350    down_write(&crypto_alg_sem);
351    alg->cra_flags |= CRYPTO_ALG_DYING;
352    up_write(&crypto_alg_sem);
353}
354EXPORT_SYMBOL_GPL(crypto_shoot_alg);
355
356struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
357                      u32 mask)
358{
359    struct crypto_tfm *tfm = NULL;
360    unsigned int tfm_size;
361    int err = -ENOMEM;
362
363    tfm_size = sizeof(*tfm) + crypto_ctxsize(alg, type, mask);
364    tfm = kzalloc(tfm_size, GFP_KERNEL);
365    if (tfm == NULL)
366        goto out_err;
367
368    tfm->__crt_alg = alg;
369
370    err = crypto_init_ops(tfm, type, mask);
371    if (err)
372        goto out_free_tfm;
373
374    if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
375        goto cra_init_failed;
376
377    goto out;
378
379cra_init_failed:
380    crypto_exit_ops(tfm);
381out_free_tfm:
382    if (err == -EAGAIN)
383        crypto_shoot_alg(alg);
384    kfree(tfm);
385out_err:
386    tfm = ERR_PTR(err);
387out:
388    return tfm;
389}
390EXPORT_SYMBOL_GPL(__crypto_alloc_tfm);
391
392/*
393 * crypto_alloc_base - Locate algorithm and allocate transform
394 * @alg_name: Name of algorithm
395 * @type: Type of algorithm
396 * @mask: Mask for type comparison
397 *
398 * This function should not be used by new algorithm types.
399 * Please use crypto_alloc_tfm instead.
400 *
401 * crypto_alloc_base() will first attempt to locate an already loaded
402 * algorithm. If that fails and the kernel supports dynamically loadable
403 * modules, it will then attempt to load a module of the same name or
404 * alias. If that fails it will send a query to any loaded crypto manager
405 * to construct an algorithm on the fly. A refcount is grabbed on the
406 * algorithm which is then associated with the new transform.
407 *
408 * The returned transform is of a non-determinate type. Most people
409 * should use one of the more specific allocation functions such as
410 * crypto_alloc_blkcipher.
411 *
412 * In case of error the return value is an error pointer.
413 */
414struct crypto_tfm *crypto_alloc_base(const char *alg_name, u32 type, u32 mask)
415{
416    struct crypto_tfm *tfm;
417    int err;
418
419    for (;;) {
420        struct crypto_alg *alg;
421
422        alg = crypto_alg_mod_lookup(alg_name, type, mask);
423        if (IS_ERR(alg)) {
424            err = PTR_ERR(alg);
425            goto err;
426        }
427
428        tfm = __crypto_alloc_tfm(alg, type, mask);
429        if (!IS_ERR(tfm))
430            return tfm;
431
432        crypto_mod_put(alg);
433        err = PTR_ERR(tfm);
434
435err:
436        if (err != -EAGAIN)
437            break;
438        if (signal_pending(current)) {
439            err = -EINTR;
440            break;
441        }
442    }
443
444    return ERR_PTR(err);
445}
446EXPORT_SYMBOL_GPL(crypto_alloc_base);
447
448void *crypto_create_tfm(struct crypto_alg *alg,
449            const struct crypto_type *frontend)
450{
451    char *mem;
452    struct crypto_tfm *tfm = NULL;
453    unsigned int tfmsize;
454    unsigned int total;
455    int err = -ENOMEM;
456
457    tfmsize = frontend->tfmsize;
458    total = tfmsize + sizeof(*tfm) + frontend->extsize(alg);
459
460    mem = kzalloc(total, GFP_KERNEL);
461    if (mem == NULL)
462        goto out_err;
463
464    tfm = (struct crypto_tfm *)(mem + tfmsize);
465    tfm->__crt_alg = alg;
466
467    err = frontend->init_tfm(tfm);
468    if (err)
469        goto out_free_tfm;
470
471    if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
472        goto cra_init_failed;
473
474    goto out;
475
476cra_init_failed:
477    crypto_exit_ops(tfm);
478out_free_tfm:
479    if (err == -EAGAIN)
480        crypto_shoot_alg(alg);
481    kfree(mem);
482out_err:
483    mem = ERR_PTR(err);
484out:
485    return mem;
486}
487EXPORT_SYMBOL_GPL(crypto_create_tfm);
488
489struct crypto_alg *crypto_find_alg(const char *alg_name,
490                   const struct crypto_type *frontend,
491                   u32 type, u32 mask)
492{
493    struct crypto_alg *(*lookup)(const char *name, u32 type, u32 mask) =
494        crypto_alg_mod_lookup;
495
496    if (frontend) {
497        type &= frontend->maskclear;
498        mask &= frontend->maskclear;
499        type |= frontend->type;
500        mask |= frontend->maskset;
501
502        if (frontend->lookup)
503            lookup = frontend->lookup;
504    }
505
506    return lookup(alg_name, type, mask);
507}
508EXPORT_SYMBOL_GPL(crypto_find_alg);
509
510/*
511 * crypto_alloc_tfm - Locate algorithm and allocate transform
512 * @alg_name: Name of algorithm
513 * @frontend: Frontend algorithm type
514 * @type: Type of algorithm
515 * @mask: Mask for type comparison
516 *
517 * crypto_alloc_tfm() will first attempt to locate an already loaded
518 * algorithm. If that fails and the kernel supports dynamically loadable
519 * modules, it will then attempt to load a module of the same name or
520 * alias. If that fails it will send a query to any loaded crypto manager
521 * to construct an algorithm on the fly. A refcount is grabbed on the
522 * algorithm which is then associated with the new transform.
523 *
524 * The returned transform is of a non-determinate type. Most people
525 * should use one of the more specific allocation functions such as
526 * crypto_alloc_blkcipher.
527 *
528 * In case of error the return value is an error pointer.
529 */
530void *crypto_alloc_tfm(const char *alg_name,
531               const struct crypto_type *frontend, u32 type, u32 mask)
532{
533    void *tfm;
534    int err;
535
536    for (;;) {
537        struct crypto_alg *alg;
538
539        alg = crypto_find_alg(alg_name, frontend, type, mask);
540        if (IS_ERR(alg)) {
541            err = PTR_ERR(alg);
542            goto err;
543        }
544
545        tfm = crypto_create_tfm(alg, frontend);
546        if (!IS_ERR(tfm))
547            return tfm;
548
549        crypto_mod_put(alg);
550        err = PTR_ERR(tfm);
551
552err:
553        if (err != -EAGAIN)
554            break;
555        if (signal_pending(current)) {
556            err = -EINTR;
557            break;
558        }
559    }
560
561    return ERR_PTR(err);
562}
563EXPORT_SYMBOL_GPL(crypto_alloc_tfm);
564
565/*
566 * crypto_destroy_tfm - Free crypto transform
567 * @mem: Start of tfm slab
568 * @tfm: Transform to free
569 *
570 * This function frees up the transform and any associated resources,
571 * then drops the refcount on the associated algorithm.
572 */
573void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
574{
575    struct crypto_alg *alg;
576
577    if (unlikely(!mem))
578        return;
579
580    alg = tfm->__crt_alg;
581
582    if (!tfm->exit && alg->cra_exit)
583        alg->cra_exit(tfm);
584    crypto_exit_ops(tfm);
585    crypto_mod_put(alg);
586    kzfree(mem);
587}
588EXPORT_SYMBOL_GPL(crypto_destroy_tfm);
589
590int crypto_has_alg(const char *name, u32 type, u32 mask)
591{
592    int ret = 0;
593    struct crypto_alg *alg = crypto_alg_mod_lookup(name, type, mask);
594
595    if (!IS_ERR(alg)) {
596        crypto_mod_put(alg);
597        ret = 1;
598    }
599
600    return ret;
601}
602EXPORT_SYMBOL_GPL(crypto_has_alg);
603
604MODULE_DESCRIPTION("Cryptographic core API");
605MODULE_LICENSE("GPL");
606

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