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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 <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 | |
23 | struct crypto_ctr_ctx { |
24 | struct crypto_cipher *child; |
25 | }; |
26 | |
27 | struct crypto_rfc3686_ctx { |
28 | struct crypto_blkcipher *child; |
29 | u8 nonce[CTR_RFC3686_NONCE_SIZE]; |
30 | }; |
31 | |
32 | static 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 | |
49 | static 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 | |
68 | static 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 | |
94 | static 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 | |
121 | static 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 | |
152 | static 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 | |
168 | static 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 | |
175 | static 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_CAST(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 | |
224 | out: |
225 | crypto_mod_put(alg); |
226 | return inst; |
227 | |
228 | out_put_alg: |
229 | inst = ERR_PTR(err); |
230 | goto out; |
231 | } |
232 | |
233 | static void crypto_ctr_free(struct crypto_instance *inst) |
234 | { |
235 | crypto_drop_spawn(crypto_instance_ctx(inst)); |
236 | kfree(inst); |
237 | } |
238 | |
239 | static 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 | |
246 | static 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 | |
272 | static 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 | |
302 | static 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 | |
318 | static 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 | |
325 | static 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 | |
377 | out: |
378 | crypto_mod_put(alg); |
379 | return inst; |
380 | |
381 | out_put_alg: |
382 | inst = ERR_PTR(err); |
383 | goto out; |
384 | } |
385 | |
386 | static 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 | |
393 | static 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 | |
405 | out: |
406 | return err; |
407 | |
408 | out_drop_ctr: |
409 | crypto_unregister_template(&crypto_ctr_tmpl); |
410 | goto out; |
411 | } |
412 | |
413 | static void __exit crypto_ctr_module_exit(void) |
414 | { |
415 | crypto_unregister_template(&crypto_rfc3686_tmpl); |
416 | crypto_unregister_template(&crypto_ctr_tmpl); |
417 | } |
418 | |
419 | module_init(crypto_ctr_module_init); |
420 | module_exit(crypto_ctr_module_exit); |
421 | |
422 | MODULE_LICENSE("GPL"); |
423 | MODULE_DESCRIPTION("CTR Counter block mode"); |
424 | MODULE_ALIAS("rfc3686"); |
425 |
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