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1// SPDX-License-Identifier: GPL-2.0-or-later2/* LRW: as defined by Cyril Guyot in3 * http://grouper.ieee.org/groups/1619/email/pdf00017.pdf4 *5 * Copyright (c) 2006 Rik Snel <rsnel@cube.dyndns.org>6 *7 * Based on ecb.c8 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>9 */10/* This implementation is checked against the test vectors in the above11 * document and by a test vector provided by Ken Buchanan at12 * https://www.mail-archive.com/stds-p1619@listserv.ieee.org/msg00173.html13 *14 * The test vectors are included in the testing module tcrypt.[ch] */15 16#include <crypto/internal/skcipher.h>17#include <crypto/scatterwalk.h>18#include <linux/err.h>19#include <linux/init.h>20#include <linux/kernel.h>21#include <linux/module.h>22#include <linux/scatterlist.h>23#include <linux/slab.h>24 25#include <crypto/b128ops.h>26#include <crypto/gf128mul.h>27 28#define LRW_BLOCK_SIZE 1629 30struct lrw_tfm_ctx {31 struct crypto_skcipher *child;32 33 /*34 * optimizes multiplying a random (non incrementing, as at the35 * start of a new sector) value with key2, we could also have36 * used 4k optimization tables or no optimization at all. In the37 * latter case we would have to store key2 here38 */39 struct gf128mul_64k *table;40 41 /*42 * stores:43 * key2*{ 0,0,...0,0,0,0,1 }, key2*{ 0,0,...0,0,0,1,1 },44 * key2*{ 0,0,...0,0,1,1,1 }, key2*{ 0,0,...0,1,1,1,1 }45 * key2*{ 0,0,...1,1,1,1,1 }, etc46 * needed for optimized multiplication of incrementing values47 * with key248 */49 be128 mulinc[128];50};51 52struct lrw_request_ctx {53 be128 t;54 struct skcipher_request subreq;55};56 57static inline void lrw_setbit128_bbe(void *b, int bit)58{59 __set_bit(bit ^ (0x80 -60#ifdef __BIG_ENDIAN61 BITS_PER_LONG62#else63 BITS_PER_BYTE64#endif65 ), b);66}67 68static int lrw_setkey(struct crypto_skcipher *parent, const u8 *key,69 unsigned int keylen)70{71 struct lrw_tfm_ctx *ctx = crypto_skcipher_ctx(parent);72 struct crypto_skcipher *child = ctx->child;73 int err, bsize = LRW_BLOCK_SIZE;74 const u8 *tweak = key + keylen - bsize;75 be128 tmp = { 0 };76 int i;77 78 crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);79 crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &80 CRYPTO_TFM_REQ_MASK);81 err = crypto_skcipher_setkey(child, key, keylen - bsize);82 if (err)83 return err;84 85 if (ctx->table)86 gf128mul_free_64k(ctx->table);87 88 /* initialize multiplication table for Key2 */89 ctx->table = gf128mul_init_64k_bbe((be128 *)tweak);90 if (!ctx->table)91 return -ENOMEM;92 93 /* initialize optimization table */94 for (i = 0; i < 128; i++) {95 lrw_setbit128_bbe(&tmp, i);96 ctx->mulinc[i] = tmp;97 gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);98 }99 100 return 0;101}102 103/*104 * Returns the number of trailing '1' bits in the words of the counter, which is105 * represented by 4 32-bit words, arranged from least to most significant.106 * At the same time, increments the counter by one.107 *108 * For example:109 *110 * u32 counter[4] = { 0xFFFFFFFF, 0x1, 0x0, 0x0 };111 * int i = lrw_next_index(&counter);112 * // i == 33, counter == { 0x0, 0x2, 0x0, 0x0 }113 */114static int lrw_next_index(u32 *counter)115{116 int i, res = 0;117 118 for (i = 0; i < 4; i++) {119 if (counter[i] + 1 != 0)120 return res + ffz(counter[i]++);121 122 counter[i] = 0;123 res += 32;124 }125 126 /*127 * If we get here, then x == 128 and we are incrementing the counter128 * from all ones to all zeros. This means we must return index 127, i.e.129 * the one corresponding to key2*{ 1,...,1 }.130 */131 return 127;132}133 134/*135 * We compute the tweak masks twice (both before and after the ECB encryption or136 * decryption) to avoid having to allocate a temporary buffer and/or make137 * mutliple calls to the 'ecb(..)' instance, which usually would be slower than138 * just doing the lrw_next_index() calls again.139 */140static int lrw_xor_tweak(struct skcipher_request *req, bool second_pass)141{142 const int bs = LRW_BLOCK_SIZE;143 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);144 const struct lrw_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);145 struct lrw_request_ctx *rctx = skcipher_request_ctx(req);146 be128 t = rctx->t;147 struct skcipher_walk w;148 __be32 *iv;149 u32 counter[4];150 int err;151 152 if (second_pass) {153 req = &rctx->subreq;154 /* set to our TFM to enforce correct alignment: */155 skcipher_request_set_tfm(req, tfm);156 }157 158 err = skcipher_walk_virt(&w, req, false);159 if (err)160 return err;161 162 iv = (__be32 *)w.iv;163 counter[0] = be32_to_cpu(iv[3]);164 counter[1] = be32_to_cpu(iv[2]);165 counter[2] = be32_to_cpu(iv[1]);166 counter[3] = be32_to_cpu(iv[0]);167 168 while (w.nbytes) {169 unsigned int avail = w.nbytes;170 be128 *wsrc;171 be128 *wdst;172 173 wsrc = w.src.virt.addr;174 wdst = w.dst.virt.addr;175 176 do {177 be128_xor(wdst++, &t, wsrc++);178 179 /* T <- I*Key2, using the optimization180 * discussed in the specification */181 be128_xor(&t, &t,182 &ctx->mulinc[lrw_next_index(counter)]);183 } while ((avail -= bs) >= bs);184 185 if (second_pass && w.nbytes == w.total) {186 iv[0] = cpu_to_be32(counter[3]);187 iv[1] = cpu_to_be32(counter[2]);188 iv[2] = cpu_to_be32(counter[1]);189 iv[3] = cpu_to_be32(counter[0]);190 }191 192 err = skcipher_walk_done(&w, avail);193 }194 195 return err;196}197 198static int lrw_xor_tweak_pre(struct skcipher_request *req)199{200 return lrw_xor_tweak(req, false);201}202 203static int lrw_xor_tweak_post(struct skcipher_request *req)204{205 return lrw_xor_tweak(req, true);206}207 208static void lrw_crypt_done(void *data, int err)209{210 struct skcipher_request *req = data;211 212 if (!err) {213 struct lrw_request_ctx *rctx = skcipher_request_ctx(req);214 215 rctx->subreq.base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;216 err = lrw_xor_tweak_post(req);217 }218 219 skcipher_request_complete(req, err);220}221 222static void lrw_init_crypt(struct skcipher_request *req)223{224 const struct lrw_tfm_ctx *ctx =225 crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));226 struct lrw_request_ctx *rctx = skcipher_request_ctx(req);227 struct skcipher_request *subreq = &rctx->subreq;228 229 skcipher_request_set_tfm(subreq, ctx->child);230 skcipher_request_set_callback(subreq, req->base.flags, lrw_crypt_done,231 req);232 /* pass req->iv as IV (will be used by xor_tweak, ECB will ignore it) */233 skcipher_request_set_crypt(subreq, req->dst, req->dst,234 req->cryptlen, req->iv);235 236 /* calculate first value of T */237 memcpy(&rctx->t, req->iv, sizeof(rctx->t));238 239 /* T <- I*Key2 */240 gf128mul_64k_bbe(&rctx->t, ctx->table);241}242 243static int lrw_encrypt(struct skcipher_request *req)244{245 struct lrw_request_ctx *rctx = skcipher_request_ctx(req);246 struct skcipher_request *subreq = &rctx->subreq;247 248 lrw_init_crypt(req);249 return lrw_xor_tweak_pre(req) ?:250 crypto_skcipher_encrypt(subreq) ?:251 lrw_xor_tweak_post(req);252}253 254static int lrw_decrypt(struct skcipher_request *req)255{256 struct lrw_request_ctx *rctx = skcipher_request_ctx(req);257 struct skcipher_request *subreq = &rctx->subreq;258 259 lrw_init_crypt(req);260 return lrw_xor_tweak_pre(req) ?:261 crypto_skcipher_decrypt(subreq) ?:262 lrw_xor_tweak_post(req);263}264 265static int lrw_init_tfm(struct crypto_skcipher *tfm)266{267 struct skcipher_instance *inst = skcipher_alg_instance(tfm);268 struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);269 struct lrw_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);270 struct crypto_skcipher *cipher;271 272 cipher = crypto_spawn_skcipher(spawn);273 if (IS_ERR(cipher))274 return PTR_ERR(cipher);275 276 ctx->child = cipher;277 278 crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(cipher) +279 sizeof(struct lrw_request_ctx));280 281 return 0;282}283 284static void lrw_exit_tfm(struct crypto_skcipher *tfm)285{286 struct lrw_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);287 288 if (ctx->table)289 gf128mul_free_64k(ctx->table);290 crypto_free_skcipher(ctx->child);291}292 293static void lrw_free_instance(struct skcipher_instance *inst)294{295 crypto_drop_skcipher(skcipher_instance_ctx(inst));296 kfree(inst);297}298 299static int lrw_create(struct crypto_template *tmpl, struct rtattr **tb)300{301 struct crypto_skcipher_spawn *spawn;302 struct skcipher_alg_common *alg;303 struct skcipher_instance *inst;304 const char *cipher_name;305 char ecb_name[CRYPTO_MAX_ALG_NAME];306 u32 mask;307 int err;308 309 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER, &mask);310 if (err)311 return err;312 313 cipher_name = crypto_attr_alg_name(tb[1]);314 if (IS_ERR(cipher_name))315 return PTR_ERR(cipher_name);316 317 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);318 if (!inst)319 return -ENOMEM;320 321 spawn = skcipher_instance_ctx(inst);322 323 err = crypto_grab_skcipher(spawn, skcipher_crypto_instance(inst),324 cipher_name, 0, mask);325 if (err == -ENOENT) {326 err = -ENAMETOOLONG;327 if (snprintf(ecb_name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",328 cipher_name) >= CRYPTO_MAX_ALG_NAME)329 goto err_free_inst;330 331 err = crypto_grab_skcipher(spawn,332 skcipher_crypto_instance(inst),333 ecb_name, 0, mask);334 }335 336 if (err)337 goto err_free_inst;338 339 alg = crypto_spawn_skcipher_alg_common(spawn);340 341 err = -EINVAL;342 if (alg->base.cra_blocksize != LRW_BLOCK_SIZE)343 goto err_free_inst;344 345 if (alg->ivsize)346 goto err_free_inst;347 348 err = crypto_inst_setname(skcipher_crypto_instance(inst), "lrw",349 &alg->base);350 if (err)351 goto err_free_inst;352 353 err = -EINVAL;354 cipher_name = alg->base.cra_name;355 356 /* Alas we screwed up the naming so we have to mangle the357 * cipher name.358 */359 if (!strncmp(cipher_name, "ecb(", 4)) {360 int len;361 362 len = strscpy(ecb_name, cipher_name + 4, sizeof(ecb_name));363 if (len < 2)364 goto err_free_inst;365 366 if (ecb_name[len - 1] != ')')367 goto err_free_inst;368 369 ecb_name[len - 1] = 0;370 371 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,372 "lrw(%s)", ecb_name) >= CRYPTO_MAX_ALG_NAME) {373 err = -ENAMETOOLONG;374 goto err_free_inst;375 }376 } else377 goto err_free_inst;378 379 inst->alg.base.cra_priority = alg->base.cra_priority;380 inst->alg.base.cra_blocksize = LRW_BLOCK_SIZE;381 inst->alg.base.cra_alignmask = alg->base.cra_alignmask |382 (__alignof__(be128) - 1);383 384 inst->alg.ivsize = LRW_BLOCK_SIZE;385 inst->alg.min_keysize = alg->min_keysize + LRW_BLOCK_SIZE;386 inst->alg.max_keysize = alg->max_keysize + LRW_BLOCK_SIZE;387 388 inst->alg.base.cra_ctxsize = sizeof(struct lrw_tfm_ctx);389 390 inst->alg.init = lrw_init_tfm;391 inst->alg.exit = lrw_exit_tfm;392 393 inst->alg.setkey = lrw_setkey;394 inst->alg.encrypt = lrw_encrypt;395 inst->alg.decrypt = lrw_decrypt;396 397 inst->free = lrw_free_instance;398 399 err = skcipher_register_instance(tmpl, inst);400 if (err) {401err_free_inst:402 lrw_free_instance(inst);403 }404 return err;405}406 407static struct crypto_template lrw_tmpl = {408 .name = "lrw",409 .create = lrw_create,410 .module = THIS_MODULE,411};412 413static int __init lrw_module_init(void)414{415 return crypto_register_template(&lrw_tmpl);416}417 418static void __exit lrw_module_exit(void)419{420 crypto_unregister_template(&lrw_tmpl);421}422 423subsys_initcall(lrw_module_init);424module_exit(lrw_module_exit);425 426MODULE_LICENSE("GPL");427MODULE_DESCRIPTION("LRW block cipher mode");428MODULE_ALIAS_CRYPTO("lrw");429MODULE_SOFTDEP("pre: ecb");430