projects/linux·blob v2.6.34 · refs

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1/*
2 * CTR: Counter mode
3 *
4 * (C) Copyright IBM Corp. 2007 - Joy Latten <[email protected]>
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 <linux/err.h>
16#include <linux/init.h>
17#include <linux/kernel.h>
18#include <linux/module.h>
19#include <linux/random.h>
20#include <linux/scatterlist.h>
21#include <linux/slab.h>
22
23struct crypto_ctr_ctx {
24 struct crypto_cipher *child;
25};
26
27struct crypto_rfc3686_ctx {
28 struct crypto_blkcipher *child;
29 u8 nonce[CTR_RFC3686_NONCE_SIZE];
30};
31
32static int crypto_ctr_setkey(struct crypto_tfm *parent, const u8 *key,
33 unsigned int keylen)
34{
35 struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(parent);
36 struct crypto_cipher *child = ctx->child;
37 int err;
38
39 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
40 crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
41 CRYPTO_TFM_REQ_MASK);
42 err = crypto_cipher_setkey(child, key, keylen);
43 crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
44 CRYPTO_TFM_RES_MASK);
45
46 return err;
47}
48
49static void crypto_ctr_crypt_final(struct blkcipher_walk *walk,
50 struct crypto_cipher *tfm)
51{
52 unsigned int bsize = crypto_cipher_blocksize(tfm);
53 unsigned long alignmask = crypto_cipher_alignmask(tfm);
54 u8 *ctrblk = walk->iv;
55 u8 tmp[bsize + alignmask];
56 u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1);
57 u8 *src = walk->src.virt.addr;
58 u8 *dst = walk->dst.virt.addr;
59 unsigned int nbytes = walk->nbytes;
60
61 crypto_cipher_encrypt_one(tfm, keystream, ctrblk);
62 crypto_xor(keystream, src, nbytes);
63 memcpy(dst, keystream, nbytes);
64
65 crypto_inc(ctrblk, bsize);
66}
67
68static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk,
69 struct crypto_cipher *tfm)
70{
71 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
72 crypto_cipher_alg(tfm)->cia_encrypt;
73 unsigned int bsize = crypto_cipher_blocksize(tfm);
74 u8 *ctrblk = walk->iv;
75 u8 *src = walk->src.virt.addr;
76 u8 *dst = walk->dst.virt.addr;
77 unsigned int nbytes = walk->nbytes;
78
79 do {
80 /* create keystream */
81 fn(crypto_cipher_tfm(tfm), dst, ctrblk);
82 crypto_xor(dst, src, bsize);
83
84 /* increment counter in counterblock */
85 crypto_inc(ctrblk, bsize);
86
87 src += bsize;
88 dst += bsize;
89 } while ((nbytes -= bsize) >= bsize);
90
91 return nbytes;
92}
93
94static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk,
95 struct crypto_cipher *tfm)
96{
97 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
98 crypto_cipher_alg(tfm)->cia_encrypt;
99 unsigned int bsize = crypto_cipher_blocksize(tfm);
100 unsigned long alignmask = crypto_cipher_alignmask(tfm);
101 unsigned int nbytes = walk->nbytes;
102 u8 *ctrblk = walk->iv;
103 u8 *src = walk->src.virt.addr;
104 u8 tmp[bsize + alignmask];
105 u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1);
106
107 do {
108 /* create keystream */
109 fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
110 crypto_xor(src, keystream, bsize);
111
112 /* increment counter in counterblock */
113 crypto_inc(ctrblk, bsize);
114
115 src += bsize;
116 } while ((nbytes -= bsize) >= bsize);
117
118 return nbytes;
119}
120
121static int crypto_ctr_crypt(struct blkcipher_desc *desc,
122 struct scatterlist *dst, struct scatterlist *src,
123 unsigned int nbytes)
124{
125 struct blkcipher_walk walk;
126 struct crypto_blkcipher *tfm = desc->tfm;
127 struct crypto_ctr_ctx *ctx = crypto_blkcipher_ctx(tfm);
128 struct crypto_cipher *child = ctx->child;
129 unsigned int bsize = crypto_cipher_blocksize(child);
130 int err;
131
132 blkcipher_walk_init(&walk, dst, src, nbytes);
133 err = blkcipher_walk_virt_block(desc, &walk, bsize);
134
135 while (walk.nbytes >= bsize) {
136 if (walk.src.virt.addr == walk.dst.virt.addr)
137 nbytes = crypto_ctr_crypt_inplace(&walk, child);
138 else
139 nbytes = crypto_ctr_crypt_segment(&walk, child);
140
141 err = blkcipher_walk_done(desc, &walk, nbytes);
142 }
143
144 if (walk.nbytes) {
145 crypto_ctr_crypt_final(&walk, child);
146 err = blkcipher_walk_done(desc, &walk, 0);
147 }
148
149 return err;
150}
151
152static int crypto_ctr_init_tfm(struct crypto_tfm *tfm)
153{
154 struct crypto_instance *inst = (void *)tfm->__crt_alg;
155 struct crypto_spawn *spawn = crypto_instance_ctx(inst);
156 struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
157 struct crypto_cipher *cipher;
158
159 cipher = crypto_spawn_cipher(spawn);
160 if (IS_ERR(cipher))
161 return PTR_ERR(cipher);
162
163 ctx->child = cipher;
164
165 return 0;
166}
167
168static void crypto_ctr_exit_tfm(struct crypto_tfm *tfm)
169{
170 struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
171
172 crypto_free_cipher(ctx->child);
173}
174
175static struct crypto_instance *crypto_ctr_alloc(struct rtattr **tb)
176{
177 struct crypto_instance *inst;
178 struct crypto_alg *alg;
179 int err;
180
181 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
182 if (err)
183 return ERR_PTR(err);
184
185 alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
186 CRYPTO_ALG_TYPE_MASK);
187 if (IS_ERR(alg))
188 return ERR_PTR(PTR_ERR(alg));
189
190 /* Block size must be >= 4 bytes. */
191 err = -EINVAL;
192 if (alg->cra_blocksize < 4)
193 goto out_put_alg;
194
195 /* If this is false we'd fail the alignment of crypto_inc. */
196 if (alg->cra_blocksize % 4)
197 goto out_put_alg;
198
199 inst = crypto_alloc_instance("ctr", alg);
200 if (IS_ERR(inst))
201 goto out;
202
203 inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
204 inst->alg.cra_priority = alg->cra_priority;
205 inst->alg.cra_blocksize = 1;
206 inst->alg.cra_alignmask = alg->cra_alignmask | (__alignof__(u32) - 1);
207 inst->alg.cra_type = &crypto_blkcipher_type;
208
209 inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
210 inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize;
211 inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize;
212
213 inst->alg.cra_ctxsize = sizeof(struct crypto_ctr_ctx);
214
215 inst->alg.cra_init = crypto_ctr_init_tfm;
216 inst->alg.cra_exit = crypto_ctr_exit_tfm;
217
218 inst->alg.cra_blkcipher.setkey = crypto_ctr_setkey;
219 inst->alg.cra_blkcipher.encrypt = crypto_ctr_crypt;
220 inst->alg.cra_blkcipher.decrypt = crypto_ctr_crypt;
221
222 inst->alg.cra_blkcipher.geniv = "chainiv";
223
224out:
225 crypto_mod_put(alg);
226 return inst;
227
228out_put_alg:
229 inst = ERR_PTR(err);
230 goto out;
231}
232
233static void crypto_ctr_free(struct crypto_instance *inst)
234{
235 crypto_drop_spawn(crypto_instance_ctx(inst));
236 kfree(inst);
237}
238
239static struct crypto_template crypto_ctr_tmpl = {
240 .name = "ctr",
241 .alloc = crypto_ctr_alloc,
242 .free = crypto_ctr_free,
243 .module = THIS_MODULE,
244};
245
246static int crypto_rfc3686_setkey(struct crypto_tfm *parent, const u8 *key,
247 unsigned int keylen)
248{
249 struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(parent);
250 struct crypto_blkcipher *child = ctx->child;
251 int err;
252
253 /* the nonce is stored in bytes at end of key */
254 if (keylen < CTR_RFC3686_NONCE_SIZE)
255 return -EINVAL;
256
257 memcpy(ctx->nonce, key + (keylen - CTR_RFC3686_NONCE_SIZE),
258 CTR_RFC3686_NONCE_SIZE);
259
260 keylen -= CTR_RFC3686_NONCE_SIZE;
261
262 crypto_blkcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
263 crypto_blkcipher_set_flags(child, crypto_tfm_get_flags(parent) &
264 CRYPTO_TFM_REQ_MASK);
265 err = crypto_blkcipher_setkey(child, key, keylen);
266 crypto_tfm_set_flags(parent, crypto_blkcipher_get_flags(child) &
267 CRYPTO_TFM_RES_MASK);
268
269 return err;
270}
271
272static int crypto_rfc3686_crypt(struct blkcipher_desc *desc,
273 struct scatterlist *dst,
274 struct scatterlist *src, unsigned int nbytes)
275{
276 struct crypto_blkcipher *tfm = desc->tfm;
277 struct crypto_rfc3686_ctx *ctx = crypto_blkcipher_ctx(tfm);
278 struct crypto_blkcipher *child = ctx->child;
279 unsigned long alignmask = crypto_blkcipher_alignmask(tfm);
280 u8 ivblk[CTR_RFC3686_BLOCK_SIZE + alignmask];
281 u8 *iv = PTR_ALIGN(ivblk + 0, alignmask + 1);
282 u8 *info = desc->info;
283 int err;
284
285 /* set up counter block */
286 memcpy(iv, ctx->nonce, CTR_RFC3686_NONCE_SIZE);
287 memcpy(iv + CTR_RFC3686_NONCE_SIZE, info, CTR_RFC3686_IV_SIZE);
288
289 /* initialize counter portion of counter block */
290 *(__be32 *)(iv + CTR_RFC3686_NONCE_SIZE + CTR_RFC3686_IV_SIZE) =
291 cpu_to_be32(1);
292
293 desc->tfm = child;
294 desc->info = iv;
295 err = crypto_blkcipher_encrypt_iv(desc, dst, src, nbytes);
296 desc->tfm = tfm;
297 desc->info = info;
298
299 return err;
300}
301
302static int crypto_rfc3686_init_tfm(struct crypto_tfm *tfm)
303{
304 struct crypto_instance *inst = (void *)tfm->__crt_alg;
305 struct crypto_spawn *spawn = crypto_instance_ctx(inst);
306 struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(tfm);
307 struct crypto_blkcipher *cipher;
308
309 cipher = crypto_spawn_blkcipher(spawn);
310 if (IS_ERR(cipher))
311 return PTR_ERR(cipher);
312
313 ctx->child = cipher;
314
315 return 0;
316}
317
318static void crypto_rfc3686_exit_tfm(struct crypto_tfm *tfm)
319{
320 struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(tfm);
321
322 crypto_free_blkcipher(ctx->child);
323}
324
325static struct crypto_instance *crypto_rfc3686_alloc(struct rtattr **tb)
326{
327 struct crypto_instance *inst;
328 struct crypto_alg *alg;
329 int err;
330
331 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
332 if (err)
333 return ERR_PTR(err);
334
335 alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_BLKCIPHER,
336 CRYPTO_ALG_TYPE_MASK);
337 err = PTR_ERR(alg);
338 if (IS_ERR(alg))
339 return ERR_PTR(err);
340
341 /* We only support 16-byte blocks. */
342 err = -EINVAL;
343 if (alg->cra_blkcipher.ivsize != CTR_RFC3686_BLOCK_SIZE)
344 goto out_put_alg;
345
346 /* Not a stream cipher? */
347 if (alg->cra_blocksize != 1)
348 goto out_put_alg;
349
350 inst = crypto_alloc_instance("rfc3686", alg);
351 if (IS_ERR(inst))
352 goto out;
353
354 inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
355 inst->alg.cra_priority = alg->cra_priority;
356 inst->alg.cra_blocksize = 1;
357 inst->alg.cra_alignmask = alg->cra_alignmask;
358 inst->alg.cra_type = &crypto_blkcipher_type;
359
360 inst->alg.cra_blkcipher.ivsize = CTR_RFC3686_IV_SIZE;
361 inst->alg.cra_blkcipher.min_keysize = alg->cra_blkcipher.min_keysize
362 + CTR_RFC3686_NONCE_SIZE;
363 inst->alg.cra_blkcipher.max_keysize = alg->cra_blkcipher.max_keysize
364 + CTR_RFC3686_NONCE_SIZE;
365
366 inst->alg.cra_blkcipher.geniv = "seqiv";
367
368 inst->alg.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx);
369
370 inst->alg.cra_init = crypto_rfc3686_init_tfm;
371 inst->alg.cra_exit = crypto_rfc3686_exit_tfm;
372
373 inst->alg.cra_blkcipher.setkey = crypto_rfc3686_setkey;
374 inst->alg.cra_blkcipher.encrypt = crypto_rfc3686_crypt;
375 inst->alg.cra_blkcipher.decrypt = crypto_rfc3686_crypt;
376
377out:
378 crypto_mod_put(alg);
379 return inst;
380
381out_put_alg:
382 inst = ERR_PTR(err);
383 goto out;
384}
385
386static struct crypto_template crypto_rfc3686_tmpl = {
387 .name = "rfc3686",
388 .alloc = crypto_rfc3686_alloc,
389 .free = crypto_ctr_free,
390 .module = THIS_MODULE,
391};
392
393static int __init crypto_ctr_module_init(void)
394{
395 int err;
396
397 err = crypto_register_template(&crypto_ctr_tmpl);
398 if (err)
399 goto out;
400
401 err = crypto_register_template(&crypto_rfc3686_tmpl);
402 if (err)
403 goto out_drop_ctr;
404
405out:
406 return err;
407
408out_drop_ctr:
409 crypto_unregister_template(&crypto_ctr_tmpl);
410 goto out;
411}
412
413static void __exit crypto_ctr_module_exit(void)
414{
415 crypto_unregister_template(&crypto_rfc3686_tmpl);
416 crypto_unregister_template(&crypto_ctr_tmpl);
417}
418
419module_init(crypto_ctr_module_init);
420module_exit(crypto_ctr_module_exit);
421
422MODULE_LICENSE("GPL");
423MODULE_DESCRIPTION("CTR Counter block mode");
424MODULE_ALIAS("rfc3686");