// SPDX-License-Identifier: GPL-2.0-or-later/* * echainiv: Encrypted Chain IV Generator * * This generator generates an IV based on a sequence number by multiplying * it with a salt and then encrypting it with the same key as used to encrypt * the plain text.  This algorithm requires that the block size be equal * to the IV size.  It is mainly useful for CBC. * * This generator can only be used by algorithms where authentication * is performed after encryption (i.e., authenc). * * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au> */ #include <crypto/internal/geniv.h>#include <crypto/scatterwalk.h>#include <crypto/skcipher.h>#include <linux/err.h>#include <linux/init.h>#include <linux/kernel.h>#include <linux/module.h>#include <linux/slab.h>#include <linux/string.h> static int echainiv_encrypt(struct aead_request *req){	struct crypto_aead *geniv = crypto_aead_reqtfm(req);	struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);	struct aead_request *subreq = aead_request_ctx(req);	__be64 nseqno;	u64 seqno;	u8 *info;	unsigned int ivsize = crypto_aead_ivsize(geniv); 	if (req->cryptlen < ivsize)		return -EINVAL; 	aead_request_set_tfm(subreq, ctx->child); 	info = req->iv; 	if (req->src != req->dst)		memcpy_sglist(req->dst, req->src,			      req->assoclen + req->cryptlen); 	aead_request_set_callback(subreq, req->base.flags,				  req->base.complete, req->base.data);	aead_request_set_crypt(subreq, req->dst, req->dst,			       req->cryptlen, info);	aead_request_set_ad(subreq, req->assoclen); 	memcpy(&nseqno, info + ivsize - 8, 8);	seqno = be64_to_cpu(nseqno);	memset(info, 0, ivsize); 	scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1); 	do {		u64 a; 		memcpy(&a, ctx->salt + ivsize - 8, 8); 		a |= 1;		a *= seqno; 		memcpy(info + ivsize - 8, &a, 8);	} while ((ivsize -= 8)); 	return crypto_aead_encrypt(subreq);} static int echainiv_decrypt(struct aead_request *req){	struct crypto_aead *geniv = crypto_aead_reqtfm(req);	struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);	struct aead_request *subreq = aead_request_ctx(req);	crypto_completion_t compl;	void *data;	unsigned int ivsize = crypto_aead_ivsize(geniv); 	if (req->cryptlen < ivsize)		return -EINVAL; 	aead_request_set_tfm(subreq, ctx->child); 	compl = req->base.complete;	data = req->base.data; 	aead_request_set_callback(subreq, req->base.flags, compl, data);	aead_request_set_crypt(subreq, req->src, req->dst,			       req->cryptlen - ivsize, req->iv);	aead_request_set_ad(subreq, req->assoclen + ivsize); 	scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0); 	return crypto_aead_decrypt(subreq);} static int echainiv_aead_create(struct crypto_template *tmpl,				struct rtattr **tb){	struct aead_instance *inst;	int err; 	inst = aead_geniv_alloc(tmpl, tb); 	if (IS_ERR(inst))		return PTR_ERR(inst); 	err = -EINVAL;	if (inst->alg.ivsize & (sizeof(u64) - 1) || !inst->alg.ivsize)		goto free_inst; 	inst->alg.encrypt = echainiv_encrypt;	inst->alg.decrypt = echainiv_decrypt; 	inst->alg.init = aead_init_geniv;	inst->alg.exit = aead_exit_geniv; 	inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx);	inst->alg.base.cra_ctxsize += inst->alg.ivsize; 	err = aead_register_instance(tmpl, inst);	if (err) {free_inst:		inst->free(inst);	}	return err;} static struct crypto_template echainiv_tmpl = {	.name = "echainiv",	.create = echainiv_aead_create,	.module = THIS_MODULE,}; static int __init echainiv_module_init(void){	return crypto_register_template(&echainiv_tmpl);} static void __exit echainiv_module_exit(void){	crypto_unregister_template(&echainiv_tmpl);} module_init(echainiv_module_init);module_exit(echainiv_module_exit); MODULE_LICENSE("GPL");MODULE_DESCRIPTION("Encrypted Chain IV Generator");MODULE_ALIAS_CRYPTO("echainiv");