Root/crypto/ctr.c

1/*
2 * CTR: Counter mode
3 *
4 * (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com>
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License as published by the Free
8 * Software Foundation; either version 2 of the License, or (at your option)
9 * any later version.
10 *
11 */
12
13#include <crypto/algapi.h>
14#include <crypto/ctr.h>
15#include <crypto/internal/skcipher.h>
16#include <linux/err.h>
17#include <linux/init.h>
18#include <linux/kernel.h>
19#include <linux/module.h>
20#include <linux/random.h>
21#include <linux/scatterlist.h>
22#include <linux/slab.h>
23
24struct crypto_ctr_ctx {
25    struct crypto_cipher *child;
26};
27
28struct crypto_rfc3686_ctx {
29    struct crypto_ablkcipher *child;
30    u8 nonce[CTR_RFC3686_NONCE_SIZE];
31};
32
33struct crypto_rfc3686_req_ctx {
34    u8 iv[CTR_RFC3686_BLOCK_SIZE];
35    struct ablkcipher_request subreq CRYPTO_MINALIGN_ATTR;
36};
37
38static int crypto_ctr_setkey(struct crypto_tfm *parent, const u8 *key,
39                 unsigned int keylen)
40{
41    struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(parent);
42    struct crypto_cipher *child = ctx->child;
43    int err;
44
45    crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
46    crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
47                CRYPTO_TFM_REQ_MASK);
48    err = crypto_cipher_setkey(child, key, keylen);
49    crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
50                 CRYPTO_TFM_RES_MASK);
51
52    return err;
53}
54
55static void crypto_ctr_crypt_final(struct blkcipher_walk *walk,
56                   struct crypto_cipher *tfm)
57{
58    unsigned int bsize = crypto_cipher_blocksize(tfm);
59    unsigned long alignmask = crypto_cipher_alignmask(tfm);
60    u8 *ctrblk = walk->iv;
61    u8 tmp[bsize + alignmask];
62    u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1);
63    u8 *src = walk->src.virt.addr;
64    u8 *dst = walk->dst.virt.addr;
65    unsigned int nbytes = walk->nbytes;
66
67    crypto_cipher_encrypt_one(tfm, keystream, ctrblk);
68    crypto_xor(keystream, src, nbytes);
69    memcpy(dst, keystream, nbytes);
70
71    crypto_inc(ctrblk, bsize);
72}
73
74static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk,
75                    struct crypto_cipher *tfm)
76{
77    void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
78           crypto_cipher_alg(tfm)->cia_encrypt;
79    unsigned int bsize = crypto_cipher_blocksize(tfm);
80    u8 *ctrblk = walk->iv;
81    u8 *src = walk->src.virt.addr;
82    u8 *dst = walk->dst.virt.addr;
83    unsigned int nbytes = walk->nbytes;
84
85    do {
86        /* create keystream */
87        fn(crypto_cipher_tfm(tfm), dst, ctrblk);
88        crypto_xor(dst, src, bsize);
89
90        /* increment counter in counterblock */
91        crypto_inc(ctrblk, bsize);
92
93        src += bsize;
94        dst += bsize;
95    } while ((nbytes -= bsize) >= bsize);
96
97    return nbytes;
98}
99
100static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk,
101                    struct crypto_cipher *tfm)
102{
103    void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
104           crypto_cipher_alg(tfm)->cia_encrypt;
105    unsigned int bsize = crypto_cipher_blocksize(tfm);
106    unsigned long alignmask = crypto_cipher_alignmask(tfm);
107    unsigned int nbytes = walk->nbytes;
108    u8 *ctrblk = walk->iv;
109    u8 *src = walk->src.virt.addr;
110    u8 tmp[bsize + alignmask];
111    u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1);
112
113    do {
114        /* create keystream */
115        fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
116        crypto_xor(src, keystream, bsize);
117
118        /* increment counter in counterblock */
119        crypto_inc(ctrblk, bsize);
120
121        src += bsize;
122    } while ((nbytes -= bsize) >= bsize);
123
124    return nbytes;
125}
126
127static int crypto_ctr_crypt(struct blkcipher_desc *desc,
128                  struct scatterlist *dst, struct scatterlist *src,
129                  unsigned int nbytes)
130{
131    struct blkcipher_walk walk;
132    struct crypto_blkcipher *tfm = desc->tfm;
133    struct crypto_ctr_ctx *ctx = crypto_blkcipher_ctx(tfm);
134    struct crypto_cipher *child = ctx->child;
135    unsigned int bsize = crypto_cipher_blocksize(child);
136    int err;
137
138    blkcipher_walk_init(&walk, dst, src, nbytes);
139    err = blkcipher_walk_virt_block(desc, &walk, bsize);
140
141    while (walk.nbytes >= bsize) {
142        if (walk.src.virt.addr == walk.dst.virt.addr)
143            nbytes = crypto_ctr_crypt_inplace(&walk, child);
144        else
145            nbytes = crypto_ctr_crypt_segment(&walk, child);
146
147        err = blkcipher_walk_done(desc, &walk, nbytes);
148    }
149
150    if (walk.nbytes) {
151        crypto_ctr_crypt_final(&walk, child);
152        err = blkcipher_walk_done(desc, &walk, 0);
153    }
154
155    return err;
156}
157
158static int crypto_ctr_init_tfm(struct crypto_tfm *tfm)
159{
160    struct crypto_instance *inst = (void *)tfm->__crt_alg;
161    struct crypto_spawn *spawn = crypto_instance_ctx(inst);
162    struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
163    struct crypto_cipher *cipher;
164
165    cipher = crypto_spawn_cipher(spawn);
166    if (IS_ERR(cipher))
167        return PTR_ERR(cipher);
168
169    ctx->child = cipher;
170
171    return 0;
172}
173
174static void crypto_ctr_exit_tfm(struct crypto_tfm *tfm)
175{
176    struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
177
178    crypto_free_cipher(ctx->child);
179}
180
181static struct crypto_instance *crypto_ctr_alloc(struct rtattr **tb)
182{
183    struct crypto_instance *inst;
184    struct crypto_alg *alg;
185    int err;
186
187    err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
188    if (err)
189        return ERR_PTR(err);
190
191    alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
192                  CRYPTO_ALG_TYPE_MASK);
193    if (IS_ERR(alg))
194        return ERR_CAST(alg);
195
196    /* Block size must be >= 4 bytes. */
197    err = -EINVAL;
198    if (alg->cra_blocksize < 4)
199        goto out_put_alg;
200
201    /* If this is false we'd fail the alignment of crypto_inc. */
202    if (alg->cra_blocksize % 4)
203        goto out_put_alg;
204
205    inst = crypto_alloc_instance("ctr", alg);
206    if (IS_ERR(inst))
207        goto out;
208
209    inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
210    inst->alg.cra_priority = alg->cra_priority;
211    inst->alg.cra_blocksize = 1;
212    inst->alg.cra_alignmask = alg->cra_alignmask | (__alignof__(u32) - 1);
213    inst->alg.cra_type = &crypto_blkcipher_type;
214
215    inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
216    inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize;
217    inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize;
218
219    inst->alg.cra_ctxsize = sizeof(struct crypto_ctr_ctx);
220
221    inst->alg.cra_init = crypto_ctr_init_tfm;
222    inst->alg.cra_exit = crypto_ctr_exit_tfm;
223
224    inst->alg.cra_blkcipher.setkey = crypto_ctr_setkey;
225    inst->alg.cra_blkcipher.encrypt = crypto_ctr_crypt;
226    inst->alg.cra_blkcipher.decrypt = crypto_ctr_crypt;
227
228    inst->alg.cra_blkcipher.geniv = "chainiv";
229
230out:
231    crypto_mod_put(alg);
232    return inst;
233
234out_put_alg:
235    inst = ERR_PTR(err);
236    goto out;
237}
238
239static void crypto_ctr_free(struct crypto_instance *inst)
240{
241    crypto_drop_spawn(crypto_instance_ctx(inst));
242    kfree(inst);
243}
244
245static struct crypto_template crypto_ctr_tmpl = {
246    .name = "ctr",
247    .alloc = crypto_ctr_alloc,
248    .free = crypto_ctr_free,
249    .module = THIS_MODULE,
250};
251
252static int crypto_rfc3686_setkey(struct crypto_ablkcipher *parent,
253                 const u8 *key, unsigned int keylen)
254{
255    struct crypto_rfc3686_ctx *ctx = crypto_ablkcipher_ctx(parent);
256    struct crypto_ablkcipher *child = ctx->child;
257    int err;
258
259    /* the nonce is stored in bytes at end of key */
260    if (keylen < CTR_RFC3686_NONCE_SIZE)
261        return -EINVAL;
262
263    memcpy(ctx->nonce, key + (keylen - CTR_RFC3686_NONCE_SIZE),
264           CTR_RFC3686_NONCE_SIZE);
265
266    keylen -= CTR_RFC3686_NONCE_SIZE;
267
268    crypto_ablkcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
269    crypto_ablkcipher_set_flags(child, crypto_ablkcipher_get_flags(parent) &
270                    CRYPTO_TFM_REQ_MASK);
271    err = crypto_ablkcipher_setkey(child, key, keylen);
272    crypto_ablkcipher_set_flags(parent, crypto_ablkcipher_get_flags(child) &
273                    CRYPTO_TFM_RES_MASK);
274
275    return err;
276}
277
278static int crypto_rfc3686_crypt(struct ablkcipher_request *req)
279{
280    struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(req);
281    struct crypto_rfc3686_ctx *ctx = crypto_ablkcipher_ctx(tfm);
282    struct crypto_ablkcipher *child = ctx->child;
283    unsigned long align = crypto_ablkcipher_alignmask(tfm);
284    struct crypto_rfc3686_req_ctx *rctx =
285        (void *)PTR_ALIGN((u8 *)ablkcipher_request_ctx(req), align + 1);
286    struct ablkcipher_request *subreq = &rctx->subreq;
287    u8 *iv = rctx->iv;
288
289    /* set up counter block */
290    memcpy(iv, ctx->nonce, CTR_RFC3686_NONCE_SIZE);
291    memcpy(iv + CTR_RFC3686_NONCE_SIZE, req->info, CTR_RFC3686_IV_SIZE);
292
293    /* initialize counter portion of counter block */
294    *(__be32 *)(iv + CTR_RFC3686_NONCE_SIZE + CTR_RFC3686_IV_SIZE) =
295        cpu_to_be32(1);
296
297    ablkcipher_request_set_tfm(subreq, child);
298    ablkcipher_request_set_callback(subreq, req->base.flags,
299                    req->base.complete, req->base.data);
300    ablkcipher_request_set_crypt(subreq, req->src, req->dst, req->nbytes,
301                     iv);
302
303    return crypto_ablkcipher_encrypt(subreq);
304}
305
306static int crypto_rfc3686_init_tfm(struct crypto_tfm *tfm)
307{
308    struct crypto_instance *inst = (void *)tfm->__crt_alg;
309    struct crypto_skcipher_spawn *spawn = crypto_instance_ctx(inst);
310    struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(tfm);
311    struct crypto_ablkcipher *cipher;
312    unsigned long align;
313
314    cipher = crypto_spawn_skcipher(spawn);
315    if (IS_ERR(cipher))
316        return PTR_ERR(cipher);
317
318    ctx->child = cipher;
319
320    align = crypto_tfm_alg_alignmask(tfm);
321    align &= ~(crypto_tfm_ctx_alignment() - 1);
322    tfm->crt_ablkcipher.reqsize = align +
323        sizeof(struct crypto_rfc3686_req_ctx) +
324        crypto_ablkcipher_reqsize(cipher);
325
326    return 0;
327}
328
329static void crypto_rfc3686_exit_tfm(struct crypto_tfm *tfm)
330{
331    struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(tfm);
332
333    crypto_free_ablkcipher(ctx->child);
334}
335
336static struct crypto_instance *crypto_rfc3686_alloc(struct rtattr **tb)
337{
338    struct crypto_attr_type *algt;
339    struct crypto_instance *inst;
340    struct crypto_alg *alg;
341    struct crypto_skcipher_spawn *spawn;
342    const char *cipher_name;
343    int err;
344
345    algt = crypto_get_attr_type(tb);
346    if (IS_ERR(algt))
347        return ERR_CAST(algt);
348
349    if ((algt->type ^ CRYPTO_ALG_TYPE_BLKCIPHER) & algt->mask)
350        return ERR_PTR(-EINVAL);
351
352    cipher_name = crypto_attr_alg_name(tb[1]);
353    if (IS_ERR(cipher_name))
354        return ERR_CAST(cipher_name);
355
356    inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
357    if (!inst)
358        return ERR_PTR(-ENOMEM);
359
360    spawn = crypto_instance_ctx(inst);
361
362    crypto_set_skcipher_spawn(spawn, inst);
363    err = crypto_grab_skcipher(spawn, cipher_name, 0,
364                   crypto_requires_sync(algt->type,
365                            algt->mask));
366    if (err)
367        goto err_free_inst;
368
369    alg = crypto_skcipher_spawn_alg(spawn);
370
371    /* We only support 16-byte blocks. */
372    err = -EINVAL;
373    if (alg->cra_ablkcipher.ivsize != CTR_RFC3686_BLOCK_SIZE)
374        goto err_drop_spawn;
375
376    /* Not a stream cipher? */
377    if (alg->cra_blocksize != 1)
378        goto err_drop_spawn;
379
380    err = -ENAMETOOLONG;
381    if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME, "rfc3686(%s)",
382             alg->cra_name) >= CRYPTO_MAX_ALG_NAME)
383        goto err_drop_spawn;
384    if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
385             "rfc3686(%s)", alg->cra_driver_name) >=
386            CRYPTO_MAX_ALG_NAME)
387        goto err_drop_spawn;
388
389    inst->alg.cra_priority = alg->cra_priority;
390    inst->alg.cra_blocksize = 1;
391    inst->alg.cra_alignmask = alg->cra_alignmask;
392
393    inst->alg.cra_flags = CRYPTO_ALG_TYPE_ABLKCIPHER |
394                  (alg->cra_flags & CRYPTO_ALG_ASYNC);
395    inst->alg.cra_type = &crypto_ablkcipher_type;
396
397    inst->alg.cra_ablkcipher.ivsize = CTR_RFC3686_IV_SIZE;
398    inst->alg.cra_ablkcipher.min_keysize =
399        alg->cra_ablkcipher.min_keysize + CTR_RFC3686_NONCE_SIZE;
400    inst->alg.cra_ablkcipher.max_keysize =
401        alg->cra_ablkcipher.max_keysize + CTR_RFC3686_NONCE_SIZE;
402
403    inst->alg.cra_ablkcipher.geniv = "seqiv";
404
405    inst->alg.cra_ablkcipher.setkey = crypto_rfc3686_setkey;
406    inst->alg.cra_ablkcipher.encrypt = crypto_rfc3686_crypt;
407    inst->alg.cra_ablkcipher.decrypt = crypto_rfc3686_crypt;
408
409    inst->alg.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx);
410
411    inst->alg.cra_init = crypto_rfc3686_init_tfm;
412    inst->alg.cra_exit = crypto_rfc3686_exit_tfm;
413
414    return inst;
415
416err_drop_spawn:
417    crypto_drop_skcipher(spawn);
418err_free_inst:
419    kfree(inst);
420    return ERR_PTR(err);
421}
422
423static void crypto_rfc3686_free(struct crypto_instance *inst)
424{
425    struct crypto_skcipher_spawn *spawn = crypto_instance_ctx(inst);
426
427    crypto_drop_skcipher(spawn);
428    kfree(inst);
429}
430
431static struct crypto_template crypto_rfc3686_tmpl = {
432    .name = "rfc3686",
433    .alloc = crypto_rfc3686_alloc,
434    .free = crypto_rfc3686_free,
435    .module = THIS_MODULE,
436};
437
438static int __init crypto_ctr_module_init(void)
439{
440    int err;
441
442    err = crypto_register_template(&crypto_ctr_tmpl);
443    if (err)
444        goto out;
445
446    err = crypto_register_template(&crypto_rfc3686_tmpl);
447    if (err)
448        goto out_drop_ctr;
449
450out:
451    return err;
452
453out_drop_ctr:
454    crypto_unregister_template(&crypto_ctr_tmpl);
455    goto out;
456}
457
458static void __exit crypto_ctr_module_exit(void)
459{
460    crypto_unregister_template(&crypto_rfc3686_tmpl);
461    crypto_unregister_template(&crypto_ctr_tmpl);
462}
463
464module_init(crypto_ctr_module_init);
465module_exit(crypto_ctr_module_exit);
466
467MODULE_LICENSE("GPL");
468MODULE_DESCRIPTION("CTR Counter block mode");
469MODULE_ALIAS("rfc3686");
470

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