diff options
Diffstat (limited to 'crypto/lrw.c')
| -rw-r--r-- | crypto/lrw.c | 431 |
1 files changed, 431 insertions, 0 deletions
diff --git a/crypto/lrw.c b/crypto/lrw.c new file mode 100644 index 000000000..fb8892ed1 --- /dev/null +++ b/crypto/lrw.c @@ -0,0 +1,431 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* LRW: as defined by Cyril Guyot in + * http://grouper.ieee.org/groups/1619/email/pdf00017.pdf + * + * Copyright (c) 2006 Rik Snel <rsnel@cube.dyndns.org> + * + * Based on ecb.c + * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au> + */ +/* This implementation is checked against the test vectors in the above + * document and by a test vector provided by Ken Buchanan at + * https://www.mail-archive.com/stds-p1619@listserv.ieee.org/msg00173.html + * + * The test vectors are included in the testing module tcrypt.[ch] */ + +#include <crypto/internal/skcipher.h> +#include <crypto/scatterwalk.h> +#include <linux/err.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/scatterlist.h> +#include <linux/slab.h> + +#include <crypto/b128ops.h> +#include <crypto/gf128mul.h> + +#define LRW_BLOCK_SIZE 16 + +struct lrw_tfm_ctx { + struct crypto_skcipher *child; + + /* + * optimizes multiplying a random (non incrementing, as at the + * start of a new sector) value with key2, we could also have + * used 4k optimization tables or no optimization at all. In the + * latter case we would have to store key2 here + */ + struct gf128mul_64k *table; + + /* + * stores: + * key2*{ 0,0,...0,0,0,0,1 }, key2*{ 0,0,...0,0,0,1,1 }, + * key2*{ 0,0,...0,0,1,1,1 }, key2*{ 0,0,...0,1,1,1,1 } + * key2*{ 0,0,...1,1,1,1,1 }, etc + * needed for optimized multiplication of incrementing values + * with key2 + */ + be128 mulinc[128]; +}; + +struct lrw_request_ctx { + be128 t; + struct skcipher_request subreq; +}; + +static inline void lrw_setbit128_bbe(void *b, int bit) +{ + __set_bit(bit ^ (0x80 - +#ifdef __BIG_ENDIAN + BITS_PER_LONG +#else + BITS_PER_BYTE +#endif + ), b); +} + +static int lrw_setkey(struct crypto_skcipher *parent, const u8 *key, + unsigned int keylen) +{ + struct lrw_tfm_ctx *ctx = crypto_skcipher_ctx(parent); + struct crypto_skcipher *child = ctx->child; + int err, bsize = LRW_BLOCK_SIZE; + const u8 *tweak = key + keylen - bsize; + be128 tmp = { 0 }; + int i; + + crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); + crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) & + CRYPTO_TFM_REQ_MASK); + err = crypto_skcipher_setkey(child, key, keylen - bsize); + if (err) + return err; + + if (ctx->table) + gf128mul_free_64k(ctx->table); + + /* initialize multiplication table for Key2 */ + ctx->table = gf128mul_init_64k_bbe((be128 *)tweak); + if (!ctx->table) + return -ENOMEM; + + /* initialize optimization table */ + for (i = 0; i < 128; i++) { + lrw_setbit128_bbe(&tmp, i); + ctx->mulinc[i] = tmp; + gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table); + } + + return 0; +} + +/* + * Returns the number of trailing '1' bits in the words of the counter, which is + * represented by 4 32-bit words, arranged from least to most significant. + * At the same time, increments the counter by one. + * + * For example: + * + * u32 counter[4] = { 0xFFFFFFFF, 0x1, 0x0, 0x0 }; + * int i = lrw_next_index(&counter); + * // i == 33, counter == { 0x0, 0x2, 0x0, 0x0 } + */ +static int lrw_next_index(u32 *counter) +{ + int i, res = 0; + + for (i = 0; i < 4; i++) { + if (counter[i] + 1 != 0) + return res + ffz(counter[i]++); + + counter[i] = 0; + res += 32; + } + + /* + * If we get here, then x == 128 and we are incrementing the counter + * from all ones to all zeros. This means we must return index 127, i.e. + * the one corresponding to key2*{ 1,...,1 }. + */ + return 127; +} + +/* + * We compute the tweak masks twice (both before and after the ECB encryption or + * decryption) to avoid having to allocate a temporary buffer and/or make + * mutliple calls to the 'ecb(..)' instance, which usually would be slower than + * just doing the lrw_next_index() calls again. + */ +static int lrw_xor_tweak(struct skcipher_request *req, bool second_pass) +{ + const int bs = LRW_BLOCK_SIZE; + struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); + const struct lrw_tfm_ctx *ctx = crypto_skcipher_ctx(tfm); + struct lrw_request_ctx *rctx = skcipher_request_ctx(req); + be128 t = rctx->t; + struct skcipher_walk w; + __be32 *iv; + u32 counter[4]; + int err; + + if (second_pass) { + req = &rctx->subreq; + /* set to our TFM to enforce correct alignment: */ + skcipher_request_set_tfm(req, tfm); + } + + err = skcipher_walk_virt(&w, req, false); + if (err) + return err; + + iv = (__be32 *)w.iv; + counter[0] = be32_to_cpu(iv[3]); + counter[1] = be32_to_cpu(iv[2]); + counter[2] = be32_to_cpu(iv[1]); + counter[3] = be32_to_cpu(iv[0]); + + while (w.nbytes) { + unsigned int avail = w.nbytes; + be128 *wsrc; + be128 *wdst; + + wsrc = w.src.virt.addr; + wdst = w.dst.virt.addr; + + do { + be128_xor(wdst++, &t, wsrc++); + + /* T <- I*Key2, using the optimization + * discussed in the specification */ + be128_xor(&t, &t, + &ctx->mulinc[lrw_next_index(counter)]); + } while ((avail -= bs) >= bs); + + if (second_pass && w.nbytes == w.total) { + iv[0] = cpu_to_be32(counter[3]); + iv[1] = cpu_to_be32(counter[2]); + iv[2] = cpu_to_be32(counter[1]); + iv[3] = cpu_to_be32(counter[0]); + } + + err = skcipher_walk_done(&w, avail); + } + + return err; +} + +static int lrw_xor_tweak_pre(struct skcipher_request *req) +{ + return lrw_xor_tweak(req, false); +} + +static int lrw_xor_tweak_post(struct skcipher_request *req) +{ + return lrw_xor_tweak(req, true); +} + +static void lrw_crypt_done(struct crypto_async_request *areq, int err) +{ + struct skcipher_request *req = areq->data; + + if (!err) { + struct lrw_request_ctx *rctx = skcipher_request_ctx(req); + + rctx->subreq.base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP; + err = lrw_xor_tweak_post(req); + } + + skcipher_request_complete(req, err); +} + +static void lrw_init_crypt(struct skcipher_request *req) +{ + const struct lrw_tfm_ctx *ctx = + crypto_skcipher_ctx(crypto_skcipher_reqtfm(req)); + struct lrw_request_ctx *rctx = skcipher_request_ctx(req); + struct skcipher_request *subreq = &rctx->subreq; + + skcipher_request_set_tfm(subreq, ctx->child); + skcipher_request_set_callback(subreq, req->base.flags, lrw_crypt_done, + req); + /* pass req->iv as IV (will be used by xor_tweak, ECB will ignore it) */ + skcipher_request_set_crypt(subreq, req->dst, req->dst, + req->cryptlen, req->iv); + + /* calculate first value of T */ + memcpy(&rctx->t, req->iv, sizeof(rctx->t)); + + /* T <- I*Key2 */ + gf128mul_64k_bbe(&rctx->t, ctx->table); +} + +static int lrw_encrypt(struct skcipher_request *req) +{ + struct lrw_request_ctx *rctx = skcipher_request_ctx(req); + struct skcipher_request *subreq = &rctx->subreq; + + lrw_init_crypt(req); + return lrw_xor_tweak_pre(req) ?: + crypto_skcipher_encrypt(subreq) ?: + lrw_xor_tweak_post(req); +} + +static int lrw_decrypt(struct skcipher_request *req) +{ + struct lrw_request_ctx *rctx = skcipher_request_ctx(req); + struct skcipher_request *subreq = &rctx->subreq; + + lrw_init_crypt(req); + return lrw_xor_tweak_pre(req) ?: + crypto_skcipher_decrypt(subreq) ?: + lrw_xor_tweak_post(req); +} + +static int lrw_init_tfm(struct crypto_skcipher *tfm) +{ + struct skcipher_instance *inst = skcipher_alg_instance(tfm); + struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst); + struct lrw_tfm_ctx *ctx = crypto_skcipher_ctx(tfm); + struct crypto_skcipher *cipher; + + cipher = crypto_spawn_skcipher(spawn); + if (IS_ERR(cipher)) + return PTR_ERR(cipher); + + ctx->child = cipher; + + crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(cipher) + + sizeof(struct lrw_request_ctx)); + + return 0; +} + +static void lrw_exit_tfm(struct crypto_skcipher *tfm) +{ + struct lrw_tfm_ctx *ctx = crypto_skcipher_ctx(tfm); + + if (ctx->table) + gf128mul_free_64k(ctx->table); + crypto_free_skcipher(ctx->child); +} + +static void lrw_free_instance(struct skcipher_instance *inst) +{ + crypto_drop_skcipher(skcipher_instance_ctx(inst)); + kfree(inst); +} + +static int lrw_create(struct crypto_template *tmpl, struct rtattr **tb) +{ + struct crypto_skcipher_spawn *spawn; + struct skcipher_instance *inst; + struct skcipher_alg *alg; + const char *cipher_name; + char ecb_name[CRYPTO_MAX_ALG_NAME]; + u32 mask; + int err; + + err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER, &mask); + if (err) + return err; + + cipher_name = crypto_attr_alg_name(tb[1]); + if (IS_ERR(cipher_name)) + return PTR_ERR(cipher_name); + + inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL); + if (!inst) + return -ENOMEM; + + spawn = skcipher_instance_ctx(inst); + + err = crypto_grab_skcipher(spawn, skcipher_crypto_instance(inst), + cipher_name, 0, mask); + if (err == -ENOENT) { + err = -ENAMETOOLONG; + if (snprintf(ecb_name, CRYPTO_MAX_ALG_NAME, "ecb(%s)", + cipher_name) >= CRYPTO_MAX_ALG_NAME) + goto err_free_inst; + + err = crypto_grab_skcipher(spawn, + skcipher_crypto_instance(inst), + ecb_name, 0, mask); + } + + if (err) + goto err_free_inst; + + alg = crypto_skcipher_spawn_alg(spawn); + + err = -EINVAL; + if (alg->base.cra_blocksize != LRW_BLOCK_SIZE) + goto err_free_inst; + + if (crypto_skcipher_alg_ivsize(alg)) + goto err_free_inst; + + err = crypto_inst_setname(skcipher_crypto_instance(inst), "lrw", + &alg->base); + if (err) + goto err_free_inst; + + err = -EINVAL; + cipher_name = alg->base.cra_name; + + /* Alas we screwed up the naming so we have to mangle the + * cipher name. + */ + if (!strncmp(cipher_name, "ecb(", 4)) { + int len; + + len = strscpy(ecb_name, cipher_name + 4, sizeof(ecb_name)); + if (len < 2) + goto err_free_inst; + + if (ecb_name[len - 1] != ')') + goto err_free_inst; + + ecb_name[len - 1] = 0; + + if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME, + "lrw(%s)", ecb_name) >= CRYPTO_MAX_ALG_NAME) { + err = -ENAMETOOLONG; + goto err_free_inst; + } + } else + goto err_free_inst; + + inst->alg.base.cra_priority = alg->base.cra_priority; + inst->alg.base.cra_blocksize = LRW_BLOCK_SIZE; + inst->alg.base.cra_alignmask = alg->base.cra_alignmask | + (__alignof__(be128) - 1); + + inst->alg.ivsize = LRW_BLOCK_SIZE; + inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) + + LRW_BLOCK_SIZE; + inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) + + LRW_BLOCK_SIZE; + + inst->alg.base.cra_ctxsize = sizeof(struct lrw_tfm_ctx); + + inst->alg.init = lrw_init_tfm; + inst->alg.exit = lrw_exit_tfm; + + inst->alg.setkey = lrw_setkey; + inst->alg.encrypt = lrw_encrypt; + inst->alg.decrypt = lrw_decrypt; + + inst->free = lrw_free_instance; + + err = skcipher_register_instance(tmpl, inst); + if (err) { +err_free_inst: + lrw_free_instance(inst); + } + return err; +} + +static struct crypto_template lrw_tmpl = { + .name = "lrw", + .create = lrw_create, + .module = THIS_MODULE, +}; + +static int __init lrw_module_init(void) +{ + return crypto_register_template(&lrw_tmpl); +} + +static void __exit lrw_module_exit(void) +{ + crypto_unregister_template(&lrw_tmpl); +} + +subsys_initcall(lrw_module_init); +module_exit(lrw_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("LRW block cipher mode"); +MODULE_ALIAS_CRYPTO("lrw"); +MODULE_SOFTDEP("pre: ecb"); |