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); 133 if (IS_ERR(inst)) 134 return PTR_ERR(inst); 135 136 alg = skcipher_ialg_simple(inst); 137 138 /* Block size must be >= 4 bytes. */ 139 err = -EINVAL; 140 if (alg->cra_blocksize < 4) 141 goto out_free_inst; 142 143 /* If this is false we'd fail the alignment of crypto_inc. */ 144 if (alg->cra_blocksize % 4) 145 goto out_free_inst; 146 147 /* CTR mode is a stream cipher. */ 148 inst->alg.base.cra_blocksize = 1; 149 150 /* 151 * To simplify the implementation, configure the skcipher walk to only 152 * give a partial block at the very end, never earlier. 153 */ 154 inst->alg.chunksize = alg->cra_blocksize; 155 156 inst->alg.encrypt = crypto_ctr_crypt; 157 inst->alg.decrypt = crypto_ctr_crypt; 158 159 err = skcipher_register_instance(tmpl, inst); 160 if (err) { 161 out_free_inst: 162 inst->free(inst); 163 } 164 165 return err; 166 } 167 168 static int crypto_rfc3686_setkey(struct crypto_skcipher *parent, 169 const u8 *key, unsigned int keylen) 170 { 171 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(parent); 172 struct crypto_skcipher *child = ctx->child; 173 int err; 174 175 /* the nonce is stored in bytes at end of key */ 176 if (keylen < CTR_RFC3686_NONCE_SIZE) 177 return -EINVAL; 178 179 memcpy(ctx->nonce, key + (keylen - CTR_RFC3686_NONCE_SIZE), 180 CTR_RFC3686_NONCE_SIZE); 181 182 keylen -= CTR_RFC3686_NONCE_SIZE; 183 184 crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); 185 crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) & 186 CRYPTO_TFM_REQ_MASK); 187 err = crypto_skcipher_setkey(child, key, keylen); 188 crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) & 189 CRYPTO_TFM_RES_MASK); 190 191 return err; 192 } 193 194 static int crypto_rfc3686_crypt(struct skcipher_request *req) 195 { 196 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); 197 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm); 198 struct crypto_skcipher *child = ctx->child; 199 unsigned long align = crypto_skcipher_alignmask(tfm); 200 struct crypto_rfc3686_req_ctx *rctx = 201 (void *)PTR_ALIGN((u8 *)skcipher_request_ctx(req), align + 1); 202 struct skcipher_request *subreq = &rctx->subreq; 203 u8 *iv = rctx->iv; 204 205 /* set up counter block */ 206 memcpy(iv, ctx->nonce, CTR_RFC3686_NONCE_SIZE); 207 memcpy(iv + CTR_RFC3686_NONCE_SIZE, req->iv, CTR_RFC3686_IV_SIZE); 208 209 /* initialize counter portion of counter block */ 210 *(__be32 *)(iv + CTR_RFC3686_NONCE_SIZE + CTR_RFC3686_IV_SIZE) = 211 cpu_to_be32(1); 212 213 skcipher_request_set_tfm(subreq, child); 214 skcipher_request_set_callback(subreq, req->base.flags, 215 req->base.complete, req->base.data); 216 skcipher_request_set_crypt(subreq, req->src, req->dst, 217 req->cryptlen, iv); 218 219 return crypto_skcipher_encrypt(subreq); 220 } 221 222 static int crypto_rfc3686_init_tfm(struct crypto_skcipher *tfm) 223 { 224 struct skcipher_instance *inst = skcipher_alg_instance(tfm); 225 struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst); 226 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm); 227 struct crypto_skcipher *cipher; 228 unsigned long align; 229 unsigned int reqsize; 230 231 cipher = crypto_spawn_skcipher(spawn); 232 if (IS_ERR(cipher)) 233 return PTR_ERR(cipher); 234 235 ctx->child = cipher; 236 237 align = crypto_skcipher_alignmask(tfm); 238 align &= ~(crypto_tfm_ctx_alignment() - 1); 239 reqsize = align + sizeof(struct crypto_rfc3686_req_ctx) + 240 crypto_skcipher_reqsize(cipher); 241 crypto_skcipher_set_reqsize(tfm, reqsize); 242 243 return 0; 244 } 245 246 static void crypto_rfc3686_exit_tfm(struct crypto_skcipher *tfm) 247 { 248 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm); 249 250 crypto_free_skcipher(ctx->child); 251 } 252 253 static void crypto_rfc3686_free(struct skcipher_instance *inst) 254 { 255 struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst); 256 257 crypto_drop_skcipher(spawn); 258 kfree(inst); 259 } 260 261 static int crypto_rfc3686_create(struct crypto_template *tmpl, 262 struct rtattr **tb) 263 { 264 struct crypto_attr_type *algt; 265 struct skcipher_instance *inst; 266 struct skcipher_alg *alg; 267 struct crypto_skcipher_spawn *spawn; 268 const char *cipher_name; 269 u32 mask; 270 271 int err; 272 273 algt = crypto_get_attr_type(tb); 274 if (IS_ERR(algt)) 275 return PTR_ERR(algt); 276 277 if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask) 278 return -EINVAL; 279 280 cipher_name = crypto_attr_alg_name(tb[1]); 281 if (IS_ERR(cipher_name)) 282 return PTR_ERR(cipher_name); 283 284 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL); 285 if (!inst) 286 return -ENOMEM; 287 288 mask = crypto_requires_sync(algt->type, algt->mask) | 289 crypto_requires_off(algt->type, algt->mask, 290 CRYPTO_ALG_NEED_FALLBACK); 291 292 spawn = skcipher_instance_ctx(inst); 293 294 crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst)); 295 err = crypto_grab_skcipher(spawn, cipher_name, 0, mask); 296 if (err) 297 goto err_free_inst; 298 299 alg = crypto_spawn_skcipher_alg(spawn); 300 301 /* We only support 16-byte blocks. */ 302 err = -EINVAL; 303 if (crypto_skcipher_alg_ivsize(alg) != CTR_RFC3686_BLOCK_SIZE) 304 goto err_drop_spawn; 305 306 /* Not a stream cipher? */ 307 if (alg->base.cra_blocksize != 1) 308 goto err_drop_spawn; 309 310 err = -ENAMETOOLONG; 311 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME, 312 "rfc3686(%s)", alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME) 313 goto err_drop_spawn; 314 if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME, 315 "rfc3686(%s)", alg->base.cra_driver_name) >= 316 CRYPTO_MAX_ALG_NAME) 317 goto err_drop_spawn; 318 319 inst->alg.base.cra_priority = alg->base.cra_priority; 320 inst->alg.base.cra_blocksize = 1; 321 inst->alg.base.cra_alignmask = alg->base.cra_alignmask; 322 323 inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC; 324 325 inst->alg.ivsize = CTR_RFC3686_IV_SIZE; 326 inst->alg.chunksize = crypto_skcipher_alg_chunksize(alg); 327 inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) + 328 CTR_RFC3686_NONCE_SIZE; 329 inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) + 330 CTR_RFC3686_NONCE_SIZE; 331 332 inst->alg.setkey = crypto_rfc3686_setkey; 333 inst->alg.encrypt = crypto_rfc3686_crypt; 334 inst->alg.decrypt = crypto_rfc3686_crypt; 335 336 inst->alg.base.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx); 337 338 inst->alg.init = crypto_rfc3686_init_tfm; 339 inst->alg.exit = crypto_rfc3686_exit_tfm; 340 341 inst->free = crypto_rfc3686_free; 342 343 err = skcipher_register_instance(tmpl, inst); 344 if (err) 345 goto err_drop_spawn; 346 347 out: 348 return err; 349 350 err_drop_spawn: 351 crypto_drop_skcipher(spawn); 352 err_free_inst: 353 kfree(inst); 354 goto out; 355 } 356 357 static struct crypto_template crypto_ctr_tmpls[] = { 358 { 359 .name = "ctr", 360 .create = crypto_ctr_create, 361 .module = THIS_MODULE, 362 }, { 363 .name = "rfc3686", 364 .create = crypto_rfc3686_create, 365 .module = THIS_MODULE, 366 }, 367 }; 368 369 static int __init crypto_ctr_module_init(void) 370 { 371 return crypto_register_templates(crypto_ctr_tmpls, 372 ARRAY_SIZE(crypto_ctr_tmpls)); 373 } 374 375 static void __exit crypto_ctr_module_exit(void) 376 { 377 crypto_unregister_templates(crypto_ctr_tmpls, 378 ARRAY_SIZE(crypto_ctr_tmpls)); 379 } 380 381 subsys_initcall(crypto_ctr_module_init); 382 module_exit(crypto_ctr_module_exit); 383 384 MODULE_LICENSE("GPL"); 385 MODULE_DESCRIPTION("CTR block cipher mode of operation"); 386 MODULE_ALIAS_CRYPTO("rfc3686"); 387 MODULE_ALIAS_CRYPTO("ctr"); 388