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