1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * CTR: Counter mode 4 * 5 * (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com> 6 */ 7 8 #include <crypto/algapi.h> 9 #include <crypto/ctr.h> 10 #include <crypto/internal/skcipher.h> 11 #include <linux/err.h> 12 #include <linux/init.h> 13 #include <linux/kernel.h> 14 #include <linux/module.h> 15 #include <linux/slab.h> 16 17 struct crypto_rfc3686_ctx { 18 struct crypto_skcipher *child; 19 u8 nonce[CTR_RFC3686_NONCE_SIZE]; 20 }; 21 22 struct crypto_rfc3686_req_ctx { 23 u8 iv[CTR_RFC3686_BLOCK_SIZE]; 24 struct skcipher_request subreq CRYPTO_MINALIGN_ATTR; 25 }; 26 27 static void crypto_ctr_crypt_final(struct skcipher_walk *walk, 28 struct crypto_cipher *tfm) 29 { 30 unsigned int bsize = crypto_cipher_blocksize(tfm); 31 unsigned long alignmask = crypto_cipher_alignmask(tfm); 32 u8 *ctrblk = walk->iv; 33 u8 tmp[MAX_CIPHER_BLOCKSIZE + MAX_CIPHER_ALIGNMASK]; 34 u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1); 35 u8 *src = walk->src.virt.addr; 36 u8 *dst = walk->dst.virt.addr; 37 unsigned int nbytes = walk->nbytes; 38 39 crypto_cipher_encrypt_one(tfm, keystream, ctrblk); 40 crypto_xor_cpy(dst, keystream, src, nbytes); 41 42 crypto_inc(ctrblk, bsize); 43 } 44 45 static int crypto_ctr_crypt_segment(struct skcipher_walk *walk, 46 struct crypto_cipher *tfm) 47 { 48 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = 49 crypto_cipher_alg(tfm)->cia_encrypt; 50 unsigned int bsize = crypto_cipher_blocksize(tfm); 51 u8 *ctrblk = walk->iv; 52 u8 *src = walk->src.virt.addr; 53 u8 *dst = walk->dst.virt.addr; 54 unsigned int nbytes = walk->nbytes; 55 56 do { 57 /* create keystream */ 58 fn(crypto_cipher_tfm(tfm), dst, ctrblk); 59 crypto_xor(dst, src, bsize); 60 61 /* increment counter in counterblock */ 62 crypto_inc(ctrblk, bsize); 63 64 src += bsize; 65 dst += bsize; 66 } while ((nbytes -= bsize) >= bsize); 67 68 return nbytes; 69 } 70 71 static int crypto_ctr_crypt_inplace(struct skcipher_walk *walk, 72 struct crypto_cipher *tfm) 73 { 74 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = 75 crypto_cipher_alg(tfm)->cia_encrypt; 76 unsigned int bsize = crypto_cipher_blocksize(tfm); 77 unsigned long alignmask = crypto_cipher_alignmask(tfm); 78 unsigned int nbytes = walk->nbytes; 79 u8 *ctrblk = walk->iv; 80 u8 *src = walk->src.virt.addr; 81 u8 tmp[MAX_CIPHER_BLOCKSIZE + MAX_CIPHER_ALIGNMASK]; 82 u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1); 83 84 do { 85 /* create keystream */ 86 fn(crypto_cipher_tfm(tfm), keystream, ctrblk); 87 crypto_xor(src, keystream, bsize); 88 89 /* increment counter in counterblock */ 90 crypto_inc(ctrblk, bsize); 91 92 src += bsize; 93 } while ((nbytes -= bsize) >= bsize); 94 95 return nbytes; 96 } 97 98 static int crypto_ctr_crypt(struct skcipher_request *req) 99 { 100 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); 101 struct crypto_cipher *cipher = skcipher_cipher_simple(tfm); 102 const unsigned int bsize = crypto_cipher_blocksize(cipher); 103 struct skcipher_walk walk; 104 unsigned int nbytes; 105 int err; 106 107 err = skcipher_walk_virt(&walk, req, false); 108 109 while (walk.nbytes >= bsize) { 110 if (walk.src.virt.addr == walk.dst.virt.addr) 111 nbytes = crypto_ctr_crypt_inplace(&walk, cipher); 112 else 113 nbytes = crypto_ctr_crypt_segment(&walk, cipher); 114 115 err = skcipher_walk_done(&walk, nbytes); 116 } 117 118 if (walk.nbytes) { 119 crypto_ctr_crypt_final(&walk, cipher); 120 err = skcipher_walk_done(&walk, 0); 121 } 122 123 return err; 124 } 125 126 static int crypto_ctr_create(struct crypto_template *tmpl, struct rtattr **tb) 127 { 128 struct skcipher_instance *inst; 129 struct crypto_alg *alg; 130 int err; 131 132 inst = skcipher_alloc_instance_simple(tmpl, tb, &alg); 133 if (IS_ERR(inst)) 134 return PTR_ERR(inst); 135 136 /* Block size must be >= 4 bytes. */ 137 err = -EINVAL; 138 if (alg->cra_blocksize < 4) 139 goto out_free_inst; 140 141 /* If this is false we'd fail the alignment of crypto_inc. */ 142 if (alg->cra_blocksize % 4) 143 goto out_free_inst; 144 145 /* CTR mode is a stream cipher. */ 146 inst->alg.base.cra_blocksize = 1; 147 148 /* 149 * To simplify the implementation, configure the skcipher walk to only 150 * give a partial block at the very end, never earlier. 151 */ 152 inst->alg.chunksize = alg->cra_blocksize; 153 154 inst->alg.encrypt = crypto_ctr_crypt; 155 inst->alg.decrypt = crypto_ctr_crypt; 156 157 err = skcipher_register_instance(tmpl, inst); 158 if (err) 159 goto out_free_inst; 160 goto out_put_alg; 161 162 out_free_inst: 163 inst->free(inst); 164 out_put_alg: 165 crypto_mod_put(alg); 166 return err; 167 } 168 169 static int crypto_rfc3686_setkey(struct crypto_skcipher *parent, 170 const u8 *key, unsigned int keylen) 171 { 172 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(parent); 173 struct crypto_skcipher *child = ctx->child; 174 int err; 175 176 /* the nonce is stored in bytes at end of key */ 177 if (keylen < CTR_RFC3686_NONCE_SIZE) 178 return -EINVAL; 179 180 memcpy(ctx->nonce, key + (keylen - CTR_RFC3686_NONCE_SIZE), 181 CTR_RFC3686_NONCE_SIZE); 182 183 keylen -= CTR_RFC3686_NONCE_SIZE; 184 185 crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); 186 crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) & 187 CRYPTO_TFM_REQ_MASK); 188 err = crypto_skcipher_setkey(child, key, keylen); 189 crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) & 190 CRYPTO_TFM_RES_MASK); 191 192 return err; 193 } 194 195 static int crypto_rfc3686_crypt(struct skcipher_request *req) 196 { 197 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); 198 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm); 199 struct crypto_skcipher *child = ctx->child; 200 unsigned long align = crypto_skcipher_alignmask(tfm); 201 struct crypto_rfc3686_req_ctx *rctx = 202 (void *)PTR_ALIGN((u8 *)skcipher_request_ctx(req), align + 1); 203 struct skcipher_request *subreq = &rctx->subreq; 204 u8 *iv = rctx->iv; 205 206 /* set up counter block */ 207 memcpy(iv, ctx->nonce, CTR_RFC3686_NONCE_SIZE); 208 memcpy(iv + CTR_RFC3686_NONCE_SIZE, req->iv, CTR_RFC3686_IV_SIZE); 209 210 /* initialize counter portion of counter block */ 211 *(__be32 *)(iv + CTR_RFC3686_NONCE_SIZE + CTR_RFC3686_IV_SIZE) = 212 cpu_to_be32(1); 213 214 skcipher_request_set_tfm(subreq, child); 215 skcipher_request_set_callback(subreq, req->base.flags, 216 req->base.complete, req->base.data); 217 skcipher_request_set_crypt(subreq, req->src, req->dst, 218 req->cryptlen, iv); 219 220 return crypto_skcipher_encrypt(subreq); 221 } 222 223 static int crypto_rfc3686_init_tfm(struct crypto_skcipher *tfm) 224 { 225 struct skcipher_instance *inst = skcipher_alg_instance(tfm); 226 struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst); 227 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm); 228 struct crypto_skcipher *cipher; 229 unsigned long align; 230 unsigned int reqsize; 231 232 cipher = crypto_spawn_skcipher(spawn); 233 if (IS_ERR(cipher)) 234 return PTR_ERR(cipher); 235 236 ctx->child = cipher; 237 238 align = crypto_skcipher_alignmask(tfm); 239 align &= ~(crypto_tfm_ctx_alignment() - 1); 240 reqsize = align + sizeof(struct crypto_rfc3686_req_ctx) + 241 crypto_skcipher_reqsize(cipher); 242 crypto_skcipher_set_reqsize(tfm, reqsize); 243 244 return 0; 245 } 246 247 static void crypto_rfc3686_exit_tfm(struct crypto_skcipher *tfm) 248 { 249 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm); 250 251 crypto_free_skcipher(ctx->child); 252 } 253 254 static void crypto_rfc3686_free(struct skcipher_instance *inst) 255 { 256 struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst); 257 258 crypto_drop_skcipher(spawn); 259 kfree(inst); 260 } 261 262 static int crypto_rfc3686_create(struct crypto_template *tmpl, 263 struct rtattr **tb) 264 { 265 struct crypto_attr_type *algt; 266 struct skcipher_instance *inst; 267 struct skcipher_alg *alg; 268 struct crypto_skcipher_spawn *spawn; 269 const char *cipher_name; 270 u32 mask; 271 272 int err; 273 274 algt = crypto_get_attr_type(tb); 275 if (IS_ERR(algt)) 276 return PTR_ERR(algt); 277 278 if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask) 279 return -EINVAL; 280 281 cipher_name = crypto_attr_alg_name(tb[1]); 282 if (IS_ERR(cipher_name)) 283 return PTR_ERR(cipher_name); 284 285 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL); 286 if (!inst) 287 return -ENOMEM; 288 289 mask = crypto_requires_sync(algt->type, algt->mask) | 290 crypto_requires_off(algt->type, algt->mask, 291 CRYPTO_ALG_NEED_FALLBACK); 292 293 spawn = skcipher_instance_ctx(inst); 294 295 crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst)); 296 err = crypto_grab_skcipher(spawn, cipher_name, 0, mask); 297 if (err) 298 goto err_free_inst; 299 300 alg = crypto_spawn_skcipher_alg(spawn); 301 302 /* We only support 16-byte blocks. */ 303 err = -EINVAL; 304 if (crypto_skcipher_alg_ivsize(alg) != CTR_RFC3686_BLOCK_SIZE) 305 goto err_drop_spawn; 306 307 /* Not a stream cipher? */ 308 if (alg->base.cra_blocksize != 1) 309 goto err_drop_spawn; 310 311 err = -ENAMETOOLONG; 312 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME, 313 "rfc3686(%s)", alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME) 314 goto err_drop_spawn; 315 if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME, 316 "rfc3686(%s)", alg->base.cra_driver_name) >= 317 CRYPTO_MAX_ALG_NAME) 318 goto err_drop_spawn; 319 320 inst->alg.base.cra_priority = alg->base.cra_priority; 321 inst->alg.base.cra_blocksize = 1; 322 inst->alg.base.cra_alignmask = alg->base.cra_alignmask; 323 324 inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC; 325 326 inst->alg.ivsize = CTR_RFC3686_IV_SIZE; 327 inst->alg.chunksize = crypto_skcipher_alg_chunksize(alg); 328 inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) + 329 CTR_RFC3686_NONCE_SIZE; 330 inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) + 331 CTR_RFC3686_NONCE_SIZE; 332 333 inst->alg.setkey = crypto_rfc3686_setkey; 334 inst->alg.encrypt = crypto_rfc3686_crypt; 335 inst->alg.decrypt = crypto_rfc3686_crypt; 336 337 inst->alg.base.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx); 338 339 inst->alg.init = crypto_rfc3686_init_tfm; 340 inst->alg.exit = crypto_rfc3686_exit_tfm; 341 342 inst->free = crypto_rfc3686_free; 343 344 err = skcipher_register_instance(tmpl, inst); 345 if (err) 346 goto err_drop_spawn; 347 348 out: 349 return err; 350 351 err_drop_spawn: 352 crypto_drop_skcipher(spawn); 353 err_free_inst: 354 kfree(inst); 355 goto out; 356 } 357 358 static struct crypto_template crypto_ctr_tmpls[] = { 359 { 360 .name = "ctr", 361 .create = crypto_ctr_create, 362 .module = THIS_MODULE, 363 }, { 364 .name = "rfc3686", 365 .create = crypto_rfc3686_create, 366 .module = THIS_MODULE, 367 }, 368 }; 369 370 static int __init crypto_ctr_module_init(void) 371 { 372 return crypto_register_templates(crypto_ctr_tmpls, 373 ARRAY_SIZE(crypto_ctr_tmpls)); 374 } 375 376 static void __exit crypto_ctr_module_exit(void) 377 { 378 crypto_unregister_templates(crypto_ctr_tmpls, 379 ARRAY_SIZE(crypto_ctr_tmpls)); 380 } 381 382 subsys_initcall(crypto_ctr_module_init); 383 module_exit(crypto_ctr_module_exit); 384 385 MODULE_LICENSE("GPL"); 386 MODULE_DESCRIPTION("CTR block cipher mode of operation"); 387 MODULE_ALIAS_CRYPTO("rfc3686"); 388 MODULE_ALIAS_CRYPTO("ctr"); 389