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 24 struct crypto_ctr_ctx { 25 struct crypto_cipher *child; 26 }; 27 28 struct crypto_rfc3686_ctx { 29 struct crypto_skcipher *child; 30 u8 nonce[CTR_RFC3686_NONCE_SIZE]; 31 }; 32 33 struct crypto_rfc3686_req_ctx { 34 u8 iv[CTR_RFC3686_BLOCK_SIZE]; 35 struct skcipher_request subreq CRYPTO_MINALIGN_ATTR; 36 }; 37 38 static 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 55 static 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 74 static 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 } 99 100 static 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 } 126 127 static 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 } 157 158 static 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 } 173 174 static 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 } 180 181 static 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; 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"; 229 230 out: 231 crypto_mod_put(alg); 232 return inst; 233 234 out_put_alg: 235 inst = ERR_PTR(err); 236 goto out; 237 } 238 239 static void crypto_ctr_free(struct crypto_instance *inst) 240 { 241 crypto_drop_spawn(crypto_instance_ctx(inst)); 242 kfree(inst); 243 } 244 245 static struct crypto_template crypto_ctr_tmpl = { 246 .name = "ctr", 247 .alloc = crypto_ctr_alloc, 248 .free = crypto_ctr_free, 249 .module = THIS_MODULE, 250 }; 251 252 static int crypto_rfc3686_setkey(struct crypto_skcipher *parent, 253 const u8 *key, unsigned int keylen) 254 { 255 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(parent); 256 struct crypto_skcipher *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_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); 269 crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) & 270 CRYPTO_TFM_REQ_MASK); 271 err = crypto_skcipher_setkey(child, key, keylen); 272 crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) & 273 CRYPTO_TFM_RES_MASK); 274 275 return err; 276 } 277 278 static int crypto_rfc3686_crypt(struct skcipher_request *req) 279 { 280 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); 281 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm); 282 struct crypto_skcipher *child = ctx->child; 283 unsigned long align = crypto_skcipher_alignmask(tfm); 284 struct crypto_rfc3686_req_ctx *rctx = 285 (void *)PTR_ALIGN((u8 *)skcipher_request_ctx(req), align + 1); 286 struct skcipher_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->iv, 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 skcipher_request_set_tfm(subreq, child); 298 skcipher_request_set_callback(subreq, req->base.flags, 299 req->base.complete, req->base.data); 300 skcipher_request_set_crypt(subreq, req->src, req->dst, 301 req->cryptlen, iv); 302 303 return crypto_skcipher_encrypt(subreq); 304 } 305 306 static int crypto_rfc3686_init_tfm(struct crypto_skcipher *tfm) 307 { 308 struct skcipher_instance *inst = skcipher_alg_instance(tfm); 309 struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst); 310 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm); 311 struct crypto_skcipher *cipher; 312 unsigned long align; 313 unsigned int reqsize; 314 315 cipher = crypto_spawn_skcipher(spawn); 316 if (IS_ERR(cipher)) 317 return PTR_ERR(cipher); 318 319 ctx->child = cipher; 320 321 align = crypto_skcipher_alignmask(tfm); 322 align &= ~(crypto_tfm_ctx_alignment() - 1); 323 reqsize = align + sizeof(struct crypto_rfc3686_req_ctx) + 324 crypto_skcipher_reqsize(cipher); 325 crypto_skcipher_set_reqsize(tfm, reqsize); 326 327 return 0; 328 } 329 330 static void crypto_rfc3686_exit_tfm(struct crypto_skcipher *tfm) 331 { 332 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm); 333 334 crypto_free_skcipher(ctx->child); 335 } 336 337 static void crypto_rfc3686_free(struct skcipher_instance *inst) 338 { 339 struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst); 340 341 crypto_drop_skcipher(spawn); 342 kfree(inst); 343 } 344 345 static int crypto_rfc3686_create(struct crypto_template *tmpl, 346 struct rtattr **tb) 347 { 348 struct crypto_attr_type *algt; 349 struct skcipher_instance *inst; 350 struct skcipher_alg *alg; 351 struct crypto_skcipher_spawn *spawn; 352 const char *cipher_name; 353 int err; 354 355 algt = crypto_get_attr_type(tb); 356 if (IS_ERR(algt)) 357 return PTR_ERR(algt); 358 359 if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask) 360 return -EINVAL; 361 362 cipher_name = crypto_attr_alg_name(tb[1]); 363 if (IS_ERR(cipher_name)) 364 return PTR_ERR(cipher_name); 365 366 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL); 367 if (!inst) 368 return -ENOMEM; 369 370 spawn = skcipher_instance_ctx(inst); 371 372 crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst)); 373 err = crypto_grab_skcipher(spawn, cipher_name, 0, 374 crypto_requires_sync(algt->type, 375 algt->mask)); 376 if (err) 377 goto err_free_inst; 378 379 alg = crypto_spawn_skcipher_alg(spawn); 380 381 /* We only support 16-byte blocks. */ 382 err = -EINVAL; 383 if (crypto_skcipher_alg_ivsize(alg) != CTR_RFC3686_BLOCK_SIZE) 384 goto err_drop_spawn; 385 386 /* Not a stream cipher? */ 387 if (alg->base.cra_blocksize != 1) 388 goto err_drop_spawn; 389 390 err = -ENAMETOOLONG; 391 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME, 392 "rfc3686(%s)", alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME) 393 goto err_drop_spawn; 394 if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME, 395 "rfc3686(%s)", alg->base.cra_driver_name) >= 396 CRYPTO_MAX_ALG_NAME) 397 goto err_drop_spawn; 398 399 inst->alg.base.cra_priority = alg->base.cra_priority; 400 inst->alg.base.cra_blocksize = 1; 401 inst->alg.base.cra_alignmask = alg->base.cra_alignmask; 402 403 inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC; 404 405 inst->alg.ivsize = CTR_RFC3686_IV_SIZE; 406 inst->alg.chunksize = crypto_skcipher_alg_chunksize(alg); 407 inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) + 408 CTR_RFC3686_NONCE_SIZE; 409 inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) + 410 CTR_RFC3686_NONCE_SIZE; 411 412 inst->alg.setkey = crypto_rfc3686_setkey; 413 inst->alg.encrypt = crypto_rfc3686_crypt; 414 inst->alg.decrypt = crypto_rfc3686_crypt; 415 416 inst->alg.base.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx); 417 418 inst->alg.init = crypto_rfc3686_init_tfm; 419 inst->alg.exit = crypto_rfc3686_exit_tfm; 420 421 inst->free = crypto_rfc3686_free; 422 423 err = skcipher_register_instance(tmpl, inst); 424 if (err) 425 goto err_drop_spawn; 426 427 out: 428 return err; 429 430 err_drop_spawn: 431 crypto_drop_skcipher(spawn); 432 err_free_inst: 433 kfree(inst); 434 goto out; 435 } 436 437 static struct crypto_template crypto_rfc3686_tmpl = { 438 .name = "rfc3686", 439 .create = crypto_rfc3686_create, 440 .module = THIS_MODULE, 441 }; 442 443 static int __init crypto_ctr_module_init(void) 444 { 445 int err; 446 447 err = crypto_register_template(&crypto_ctr_tmpl); 448 if (err) 449 goto out; 450 451 err = crypto_register_template(&crypto_rfc3686_tmpl); 452 if (err) 453 goto out_drop_ctr; 454 455 out: 456 return err; 457 458 out_drop_ctr: 459 crypto_unregister_template(&crypto_ctr_tmpl); 460 goto out; 461 } 462 463 static void __exit crypto_ctr_module_exit(void) 464 { 465 crypto_unregister_template(&crypto_rfc3686_tmpl); 466 crypto_unregister_template(&crypto_ctr_tmpl); 467 } 468 469 module_init(crypto_ctr_module_init); 470 module_exit(crypto_ctr_module_exit); 471 472 MODULE_LICENSE("GPL"); 473 MODULE_DESCRIPTION("CTR Counter block mode"); 474 MODULE_ALIAS_CRYPTO("rfc3686"); 475 MODULE_ALIAS_CRYPTO("ctr"); 476