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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"); |