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// 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 * multiple 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;		const 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(void *data, int err){	struct skcipher_request *req = 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_alg_common *alg;	struct skcipher_instance *inst;	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 && memcmp(cipher_name, "ecb(", 4)) {		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_spawn_skcipher_alg_common(spawn); 	err = -EINVAL;	if (alg->base.cra_blocksize != LRW_BLOCK_SIZE)		goto err_free_inst; 	if (alg->ivsize)		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 (!memcmp(cipher_name, "ecb(", 4)) {		int len; 		len = strscpy(ecb_name, cipher_name + 4);		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 = alg->min_keysize + LRW_BLOCK_SIZE;	inst->alg.max_keysize = alg->max_keysize + 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);} module_init(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");