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_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 out: 223 crypto_mod_put(alg); 224 return inst; 225 226 out_put_alg: 227 inst = ERR_PTR(err); 228 goto out; 229 } 230 231 static void crypto_ctr_free(struct crypto_instance *inst) 232 { 233 crypto_drop_spawn(crypto_instance_ctx(inst)); 234 kfree(inst); 235 } 236 237 static struct crypto_template crypto_ctr_tmpl = { 238 .name = "ctr", 239 .alloc = crypto_ctr_alloc, 240 .free = crypto_ctr_free, 241 .module = THIS_MODULE, 242 }; 243 244 static int crypto_rfc3686_setkey(struct crypto_tfm *parent, const u8 *key, 245 unsigned int keylen) 246 { 247 struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(parent); 248 struct crypto_blkcipher *child = ctx->child; 249 int err; 250 251 /* the nonce is stored in bytes at end of key */ 252 if (keylen < CTR_RFC3686_NONCE_SIZE) 253 return -EINVAL; 254 255 memcpy(ctx->nonce, key + (keylen - CTR_RFC3686_NONCE_SIZE), 256 CTR_RFC3686_NONCE_SIZE); 257 258 keylen -= CTR_RFC3686_NONCE_SIZE; 259 260 crypto_blkcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); 261 crypto_blkcipher_set_flags(child, crypto_tfm_get_flags(parent) & 262 CRYPTO_TFM_REQ_MASK); 263 err = crypto_blkcipher_setkey(child, key, keylen); 264 crypto_tfm_set_flags(parent, crypto_blkcipher_get_flags(child) & 265 CRYPTO_TFM_RES_MASK); 266 267 return err; 268 } 269 270 static int crypto_rfc3686_crypt(struct blkcipher_desc *desc, 271 struct scatterlist *dst, 272 struct scatterlist *src, unsigned int nbytes) 273 { 274 struct crypto_blkcipher *tfm = desc->tfm; 275 struct crypto_rfc3686_ctx *ctx = crypto_blkcipher_ctx(tfm); 276 struct crypto_blkcipher *child = ctx->child; 277 unsigned long alignmask = crypto_blkcipher_alignmask(tfm); 278 u8 ivblk[CTR_RFC3686_BLOCK_SIZE + alignmask]; 279 u8 *iv = PTR_ALIGN(ivblk + 0, alignmask + 1); 280 u8 *info = desc->info; 281 int err; 282 283 /* set up counter block */ 284 memcpy(iv, ctx->nonce, CTR_RFC3686_NONCE_SIZE); 285 memcpy(iv + CTR_RFC3686_NONCE_SIZE, info, CTR_RFC3686_IV_SIZE); 286 287 /* initialize counter portion of counter block */ 288 *(__be32 *)(iv + CTR_RFC3686_NONCE_SIZE + CTR_RFC3686_IV_SIZE) = 289 cpu_to_be32(1); 290 291 desc->tfm = child; 292 desc->info = iv; 293 err = crypto_blkcipher_encrypt_iv(desc, dst, src, nbytes); 294 desc->tfm = tfm; 295 desc->info = info; 296 297 return err; 298 } 299 300 static int crypto_rfc3686_init_tfm(struct crypto_tfm *tfm) 301 { 302 struct crypto_instance *inst = (void *)tfm->__crt_alg; 303 struct crypto_spawn *spawn = crypto_instance_ctx(inst); 304 struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(tfm); 305 struct crypto_blkcipher *cipher; 306 307 cipher = crypto_spawn_blkcipher(spawn); 308 if (IS_ERR(cipher)) 309 return PTR_ERR(cipher); 310 311 ctx->child = cipher; 312 313 return 0; 314 } 315 316 static void crypto_rfc3686_exit_tfm(struct crypto_tfm *tfm) 317 { 318 struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(tfm); 319 320 crypto_free_blkcipher(ctx->child); 321 } 322 323 static struct crypto_instance *crypto_rfc3686_alloc(struct rtattr **tb) 324 { 325 struct crypto_instance *inst; 326 struct crypto_alg *alg; 327 int err; 328 329 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER); 330 if (err) 331 return ERR_PTR(err); 332 333 alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_BLKCIPHER, 334 CRYPTO_ALG_TYPE_MASK); 335 err = PTR_ERR(alg); 336 if (IS_ERR(alg)) 337 return ERR_PTR(err); 338 339 /* We only support 16-byte blocks. */ 340 err = -EINVAL; 341 if (alg->cra_blkcipher.ivsize != CTR_RFC3686_BLOCK_SIZE) 342 goto out_put_alg; 343 344 /* Not a stream cipher? */ 345 if (alg->cra_blocksize != 1) 346 goto out_put_alg; 347 348 inst = crypto_alloc_instance("rfc3686", alg); 349 if (IS_ERR(inst)) 350 goto out; 351 352 inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER; 353 inst->alg.cra_priority = alg->cra_priority; 354 inst->alg.cra_blocksize = 1; 355 inst->alg.cra_alignmask = alg->cra_alignmask; 356 inst->alg.cra_type = &crypto_blkcipher_type; 357 358 inst->alg.cra_blkcipher.ivsize = CTR_RFC3686_IV_SIZE; 359 inst->alg.cra_blkcipher.min_keysize = alg->cra_blkcipher.min_keysize 360 + CTR_RFC3686_NONCE_SIZE; 361 inst->alg.cra_blkcipher.max_keysize = alg->cra_blkcipher.max_keysize 362 + CTR_RFC3686_NONCE_SIZE; 363 364 inst->alg.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx); 365 366 inst->alg.cra_init = crypto_rfc3686_init_tfm; 367 inst->alg.cra_exit = crypto_rfc3686_exit_tfm; 368 369 inst->alg.cra_blkcipher.setkey = crypto_rfc3686_setkey; 370 inst->alg.cra_blkcipher.encrypt = crypto_rfc3686_crypt; 371 inst->alg.cra_blkcipher.decrypt = crypto_rfc3686_crypt; 372 373 out: 374 crypto_mod_put(alg); 375 return inst; 376 377 out_put_alg: 378 inst = ERR_PTR(err); 379 goto out; 380 } 381 382 static struct crypto_template crypto_rfc3686_tmpl = { 383 .name = "rfc3686", 384 .alloc = crypto_rfc3686_alloc, 385 .free = crypto_ctr_free, 386 .module = THIS_MODULE, 387 }; 388 389 static int __init crypto_ctr_module_init(void) 390 { 391 int err; 392 393 err = crypto_register_template(&crypto_ctr_tmpl); 394 if (err) 395 goto out; 396 397 err = crypto_register_template(&crypto_rfc3686_tmpl); 398 if (err) 399 goto out_drop_ctr; 400 401 out: 402 return err; 403 404 out_drop_ctr: 405 crypto_unregister_template(&crypto_ctr_tmpl); 406 goto out; 407 } 408 409 static void __exit crypto_ctr_module_exit(void) 410 { 411 crypto_unregister_template(&crypto_rfc3686_tmpl); 412 crypto_unregister_template(&crypto_ctr_tmpl); 413 } 414 415 module_init(crypto_ctr_module_init); 416 module_exit(crypto_ctr_module_exit); 417 418 MODULE_LICENSE("GPL"); 419 MODULE_DESCRIPTION("CTR Counter block mode"); 420 MODULE_ALIAS("rfc3686"); 421