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; 173 174 /* the nonce is stored in bytes at end of key */ 175 if (keylen < CTR_RFC3686_NONCE_SIZE) 176 return -EINVAL; 177 178 memcpy(ctx->nonce, key + (keylen - CTR_RFC3686_NONCE_SIZE), 179 CTR_RFC3686_NONCE_SIZE); 180 181 keylen -= CTR_RFC3686_NONCE_SIZE; 182 183 crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); 184 crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) & 185 CRYPTO_TFM_REQ_MASK); 186 return crypto_skcipher_setkey(child, key, keylen); 187 } 188 189 static int crypto_rfc3686_crypt(struct skcipher_request *req) 190 { 191 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); 192 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm); 193 struct crypto_skcipher *child = ctx->child; 194 unsigned long align = crypto_skcipher_alignmask(tfm); 195 struct crypto_rfc3686_req_ctx *rctx = 196 (void *)PTR_ALIGN((u8 *)skcipher_request_ctx(req), align + 1); 197 struct skcipher_request *subreq = &rctx->subreq; 198 u8 *iv = rctx->iv; 199 200 /* set up counter block */ 201 memcpy(iv, ctx->nonce, CTR_RFC3686_NONCE_SIZE); 202 memcpy(iv + CTR_RFC3686_NONCE_SIZE, req->iv, CTR_RFC3686_IV_SIZE); 203 204 /* initialize counter portion of counter block */ 205 *(__be32 *)(iv + CTR_RFC3686_NONCE_SIZE + CTR_RFC3686_IV_SIZE) = 206 cpu_to_be32(1); 207 208 skcipher_request_set_tfm(subreq, child); 209 skcipher_request_set_callback(subreq, req->base.flags, 210 req->base.complete, req->base.data); 211 skcipher_request_set_crypt(subreq, req->src, req->dst, 212 req->cryptlen, iv); 213 214 return crypto_skcipher_encrypt(subreq); 215 } 216 217 static int crypto_rfc3686_init_tfm(struct crypto_skcipher *tfm) 218 { 219 struct skcipher_instance *inst = skcipher_alg_instance(tfm); 220 struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst); 221 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm); 222 struct crypto_skcipher *cipher; 223 unsigned long align; 224 unsigned int reqsize; 225 226 cipher = crypto_spawn_skcipher(spawn); 227 if (IS_ERR(cipher)) 228 return PTR_ERR(cipher); 229 230 ctx->child = cipher; 231 232 align = crypto_skcipher_alignmask(tfm); 233 align &= ~(crypto_tfm_ctx_alignment() - 1); 234 reqsize = align + sizeof(struct crypto_rfc3686_req_ctx) + 235 crypto_skcipher_reqsize(cipher); 236 crypto_skcipher_set_reqsize(tfm, reqsize); 237 238 return 0; 239 } 240 241 static void crypto_rfc3686_exit_tfm(struct crypto_skcipher *tfm) 242 { 243 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm); 244 245 crypto_free_skcipher(ctx->child); 246 } 247 248 static void crypto_rfc3686_free(struct skcipher_instance *inst) 249 { 250 struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst); 251 252 crypto_drop_skcipher(spawn); 253 kfree(inst); 254 } 255 256 static int crypto_rfc3686_create(struct crypto_template *tmpl, 257 struct rtattr **tb) 258 { 259 struct skcipher_instance *inst; 260 struct skcipher_alg *alg; 261 struct crypto_skcipher_spawn *spawn; 262 u32 mask; 263 int err; 264 265 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER, &mask); 266 if (err) 267 return err; 268 269 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL); 270 if (!inst) 271 return -ENOMEM; 272 273 spawn = skcipher_instance_ctx(inst); 274 275 err = crypto_grab_skcipher(spawn, skcipher_crypto_instance(inst), 276 crypto_attr_alg_name(tb[1]), 0, mask); 277 if (err) 278 goto err_free_inst; 279 280 alg = crypto_spawn_skcipher_alg(spawn); 281 282 /* We only support 16-byte blocks. */ 283 err = -EINVAL; 284 if (crypto_skcipher_alg_ivsize(alg) != CTR_RFC3686_BLOCK_SIZE) 285 goto err_free_inst; 286 287 /* Not a stream cipher? */ 288 if (alg->base.cra_blocksize != 1) 289 goto err_free_inst; 290 291 err = -ENAMETOOLONG; 292 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME, 293 "rfc3686(%s)", alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME) 294 goto err_free_inst; 295 if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME, 296 "rfc3686(%s)", alg->base.cra_driver_name) >= 297 CRYPTO_MAX_ALG_NAME) 298 goto err_free_inst; 299 300 inst->alg.base.cra_priority = alg->base.cra_priority; 301 inst->alg.base.cra_blocksize = 1; 302 inst->alg.base.cra_alignmask = alg->base.cra_alignmask; 303 304 inst->alg.ivsize = CTR_RFC3686_IV_SIZE; 305 inst->alg.chunksize = crypto_skcipher_alg_chunksize(alg); 306 inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) + 307 CTR_RFC3686_NONCE_SIZE; 308 inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) + 309 CTR_RFC3686_NONCE_SIZE; 310 311 inst->alg.setkey = crypto_rfc3686_setkey; 312 inst->alg.encrypt = crypto_rfc3686_crypt; 313 inst->alg.decrypt = crypto_rfc3686_crypt; 314 315 inst->alg.base.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx); 316 317 inst->alg.init = crypto_rfc3686_init_tfm; 318 inst->alg.exit = crypto_rfc3686_exit_tfm; 319 320 inst->free = crypto_rfc3686_free; 321 322 err = skcipher_register_instance(tmpl, inst); 323 if (err) { 324 err_free_inst: 325 crypto_rfc3686_free(inst); 326 } 327 return err; 328 } 329 330 static struct crypto_template crypto_ctr_tmpls[] = { 331 { 332 .name = "ctr", 333 .create = crypto_ctr_create, 334 .module = THIS_MODULE, 335 }, { 336 .name = "rfc3686", 337 .create = crypto_rfc3686_create, 338 .module = THIS_MODULE, 339 }, 340 }; 341 342 static int __init crypto_ctr_module_init(void) 343 { 344 return crypto_register_templates(crypto_ctr_tmpls, 345 ARRAY_SIZE(crypto_ctr_tmpls)); 346 } 347 348 static void __exit crypto_ctr_module_exit(void) 349 { 350 crypto_unregister_templates(crypto_ctr_tmpls, 351 ARRAY_SIZE(crypto_ctr_tmpls)); 352 } 353 354 subsys_initcall(crypto_ctr_module_init); 355 module_exit(crypto_ctr_module_exit); 356 357 MODULE_LICENSE("GPL"); 358 MODULE_DESCRIPTION("CTR block cipher mode of operation"); 359 MODULE_ALIAS_CRYPTO("rfc3686"); 360 MODULE_ALIAS_CRYPTO("ctr"); 361