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_attr_type *algt; 185 struct crypto_alg *alg; 186 u32 mask; 187 int err; 188 189 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER); 190 if (err) 191 return ERR_PTR(err); 192 193 algt = crypto_get_attr_type(tb); 194 if (IS_ERR(algt)) 195 return ERR_CAST(algt); 196 197 mask = CRYPTO_ALG_TYPE_MASK | 198 crypto_requires_off(algt->type, algt->mask, 199 CRYPTO_ALG_NEED_FALLBACK); 200 201 alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER, mask); 202 if (IS_ERR(alg)) 203 return ERR_CAST(alg); 204 205 /* Block size must be >= 4 bytes. */ 206 err = -EINVAL; 207 if (alg->cra_blocksize < 4) 208 goto out_put_alg; 209 210 /* If this is false we'd fail the alignment of crypto_inc. */ 211 if (alg->cra_blocksize % 4) 212 goto out_put_alg; 213 214 inst = crypto_alloc_instance("ctr", alg); 215 if (IS_ERR(inst)) 216 goto out; 217 218 inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER; 219 inst->alg.cra_priority = alg->cra_priority; 220 inst->alg.cra_blocksize = 1; 221 inst->alg.cra_alignmask = alg->cra_alignmask; 222 inst->alg.cra_type = &crypto_blkcipher_type; 223 224 inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize; 225 inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize; 226 inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize; 227 228 inst->alg.cra_ctxsize = sizeof(struct crypto_ctr_ctx); 229 230 inst->alg.cra_init = crypto_ctr_init_tfm; 231 inst->alg.cra_exit = crypto_ctr_exit_tfm; 232 233 inst->alg.cra_blkcipher.setkey = crypto_ctr_setkey; 234 inst->alg.cra_blkcipher.encrypt = crypto_ctr_crypt; 235 inst->alg.cra_blkcipher.decrypt = crypto_ctr_crypt; 236 237 inst->alg.cra_blkcipher.geniv = "chainiv"; 238 239 out: 240 crypto_mod_put(alg); 241 return inst; 242 243 out_put_alg: 244 inst = ERR_PTR(err); 245 goto out; 246 } 247 248 static void crypto_ctr_free(struct crypto_instance *inst) 249 { 250 crypto_drop_spawn(crypto_instance_ctx(inst)); 251 kfree(inst); 252 } 253 254 static struct crypto_template crypto_ctr_tmpl = { 255 .name = "ctr", 256 .alloc = crypto_ctr_alloc, 257 .free = crypto_ctr_free, 258 .module = THIS_MODULE, 259 }; 260 261 static int crypto_rfc3686_setkey(struct crypto_skcipher *parent, 262 const u8 *key, unsigned int keylen) 263 { 264 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(parent); 265 struct crypto_skcipher *child = ctx->child; 266 int err; 267 268 /* the nonce is stored in bytes at end of key */ 269 if (keylen < CTR_RFC3686_NONCE_SIZE) 270 return -EINVAL; 271 272 memcpy(ctx->nonce, key + (keylen - CTR_RFC3686_NONCE_SIZE), 273 CTR_RFC3686_NONCE_SIZE); 274 275 keylen -= CTR_RFC3686_NONCE_SIZE; 276 277 crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); 278 crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) & 279 CRYPTO_TFM_REQ_MASK); 280 err = crypto_skcipher_setkey(child, key, keylen); 281 crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) & 282 CRYPTO_TFM_RES_MASK); 283 284 return err; 285 } 286 287 static int crypto_rfc3686_crypt(struct skcipher_request *req) 288 { 289 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); 290 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm); 291 struct crypto_skcipher *child = ctx->child; 292 unsigned long align = crypto_skcipher_alignmask(tfm); 293 struct crypto_rfc3686_req_ctx *rctx = 294 (void *)PTR_ALIGN((u8 *)skcipher_request_ctx(req), align + 1); 295 struct skcipher_request *subreq = &rctx->subreq; 296 u8 *iv = rctx->iv; 297 298 /* set up counter block */ 299 memcpy(iv, ctx->nonce, CTR_RFC3686_NONCE_SIZE); 300 memcpy(iv + CTR_RFC3686_NONCE_SIZE, req->iv, CTR_RFC3686_IV_SIZE); 301 302 /* initialize counter portion of counter block */ 303 *(__be32 *)(iv + CTR_RFC3686_NONCE_SIZE + CTR_RFC3686_IV_SIZE) = 304 cpu_to_be32(1); 305 306 skcipher_request_set_tfm(subreq, child); 307 skcipher_request_set_callback(subreq, req->base.flags, 308 req->base.complete, req->base.data); 309 skcipher_request_set_crypt(subreq, req->src, req->dst, 310 req->cryptlen, iv); 311 312 return crypto_skcipher_encrypt(subreq); 313 } 314 315 static int crypto_rfc3686_init_tfm(struct crypto_skcipher *tfm) 316 { 317 struct skcipher_instance *inst = skcipher_alg_instance(tfm); 318 struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst); 319 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm); 320 struct crypto_skcipher *cipher; 321 unsigned long align; 322 unsigned int reqsize; 323 324 cipher = crypto_spawn_skcipher(spawn); 325 if (IS_ERR(cipher)) 326 return PTR_ERR(cipher); 327 328 ctx->child = cipher; 329 330 align = crypto_skcipher_alignmask(tfm); 331 align &= ~(crypto_tfm_ctx_alignment() - 1); 332 reqsize = align + sizeof(struct crypto_rfc3686_req_ctx) + 333 crypto_skcipher_reqsize(cipher); 334 crypto_skcipher_set_reqsize(tfm, reqsize); 335 336 return 0; 337 } 338 339 static void crypto_rfc3686_exit_tfm(struct crypto_skcipher *tfm) 340 { 341 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm); 342 343 crypto_free_skcipher(ctx->child); 344 } 345 346 static void crypto_rfc3686_free(struct skcipher_instance *inst) 347 { 348 struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst); 349 350 crypto_drop_skcipher(spawn); 351 kfree(inst); 352 } 353 354 static int crypto_rfc3686_create(struct crypto_template *tmpl, 355 struct rtattr **tb) 356 { 357 struct crypto_attr_type *algt; 358 struct skcipher_instance *inst; 359 struct skcipher_alg *alg; 360 struct crypto_skcipher_spawn *spawn; 361 const char *cipher_name; 362 u32 mask; 363 364 int err; 365 366 algt = crypto_get_attr_type(tb); 367 if (IS_ERR(algt)) 368 return PTR_ERR(algt); 369 370 if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask) 371 return -EINVAL; 372 373 cipher_name = crypto_attr_alg_name(tb[1]); 374 if (IS_ERR(cipher_name)) 375 return PTR_ERR(cipher_name); 376 377 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL); 378 if (!inst) 379 return -ENOMEM; 380 381 mask = crypto_requires_sync(algt->type, algt->mask) | 382 crypto_requires_off(algt->type, algt->mask, 383 CRYPTO_ALG_NEED_FALLBACK); 384 385 spawn = skcipher_instance_ctx(inst); 386 387 crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst)); 388 err = crypto_grab_skcipher(spawn, cipher_name, 0, mask); 389 if (err) 390 goto err_free_inst; 391 392 alg = crypto_spawn_skcipher_alg(spawn); 393 394 /* We only support 16-byte blocks. */ 395 err = -EINVAL; 396 if (crypto_skcipher_alg_ivsize(alg) != CTR_RFC3686_BLOCK_SIZE) 397 goto err_drop_spawn; 398 399 /* Not a stream cipher? */ 400 if (alg->base.cra_blocksize != 1) 401 goto err_drop_spawn; 402 403 err = -ENAMETOOLONG; 404 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME, 405 "rfc3686(%s)", alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME) 406 goto err_drop_spawn; 407 if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME, 408 "rfc3686(%s)", alg->base.cra_driver_name) >= 409 CRYPTO_MAX_ALG_NAME) 410 goto err_drop_spawn; 411 412 inst->alg.base.cra_priority = alg->base.cra_priority; 413 inst->alg.base.cra_blocksize = 1; 414 inst->alg.base.cra_alignmask = alg->base.cra_alignmask; 415 416 inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC; 417 418 inst->alg.ivsize = CTR_RFC3686_IV_SIZE; 419 inst->alg.chunksize = crypto_skcipher_alg_chunksize(alg); 420 inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) + 421 CTR_RFC3686_NONCE_SIZE; 422 inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) + 423 CTR_RFC3686_NONCE_SIZE; 424 425 inst->alg.setkey = crypto_rfc3686_setkey; 426 inst->alg.encrypt = crypto_rfc3686_crypt; 427 inst->alg.decrypt = crypto_rfc3686_crypt; 428 429 inst->alg.base.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx); 430 431 inst->alg.init = crypto_rfc3686_init_tfm; 432 inst->alg.exit = crypto_rfc3686_exit_tfm; 433 434 inst->free = crypto_rfc3686_free; 435 436 err = skcipher_register_instance(tmpl, inst); 437 if (err) 438 goto err_drop_spawn; 439 440 out: 441 return err; 442 443 err_drop_spawn: 444 crypto_drop_skcipher(spawn); 445 err_free_inst: 446 kfree(inst); 447 goto out; 448 } 449 450 static struct crypto_template crypto_rfc3686_tmpl = { 451 .name = "rfc3686", 452 .create = crypto_rfc3686_create, 453 .module = THIS_MODULE, 454 }; 455 456 static int __init crypto_ctr_module_init(void) 457 { 458 int err; 459 460 err = crypto_register_template(&crypto_ctr_tmpl); 461 if (err) 462 goto out; 463 464 err = crypto_register_template(&crypto_rfc3686_tmpl); 465 if (err) 466 goto out_drop_ctr; 467 468 out: 469 return err; 470 471 out_drop_ctr: 472 crypto_unregister_template(&crypto_ctr_tmpl); 473 goto out; 474 } 475 476 static void __exit crypto_ctr_module_exit(void) 477 { 478 crypto_unregister_template(&crypto_rfc3686_tmpl); 479 crypto_unregister_template(&crypto_ctr_tmpl); 480 } 481 482 module_init(crypto_ctr_module_init); 483 module_exit(crypto_ctr_module_exit); 484 485 MODULE_LICENSE("GPL"); 486 MODULE_DESCRIPTION("CTR Counter block mode"); 487 MODULE_ALIAS_CRYPTO("rfc3686"); 488 MODULE_ALIAS_CRYPTO("ctr"); 489