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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* seqiv: Sequence Number IV Generator
*
* This generator generates an IV based on a sequence number by xoring it
* with a salt. This algorithm is mainly useful for CTR and similar modes.
*
* Copyright (c) 2007 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 void seqiv_aead_encrypt_complete2(struct aead_request *req, int err)
{
struct aead_request *subreq = aead_request_ctx(req);
struct crypto_aead *geniv;
if (err == -EINPROGRESS)
return;
if (err)
goto out;
geniv = crypto_aead_reqtfm(req);
memcpy(req->iv, subreq->iv, crypto_aead_ivsize(geniv));
out:
kfree_sensitive(subreq->iv);
}
static void seqiv_aead_encrypt_complete(struct crypto_async_request *base,
int err)
{
struct aead_request *req = base->data;
seqiv_aead_encrypt_complete2(req, err);
aead_request_complete(req, err);
}
static int seqiv_aead_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);
crypto_completion_t compl;
void *data;
u8 *info;
unsigned int ivsize = 8;
int err;
if (req->cryptlen < ivsize)
return -EINVAL;
aead_request_set_tfm(subreq, ctx->child);
compl = req->base.complete;
data = req->base.data;
info = req->iv;
if (req->src != req->dst) {
SYNC_SKCIPHER_REQUEST_ON_STACK(nreq, ctx->sknull);
skcipher_request_set_sync_tfm(nreq, ctx->sknull);
skcipher_request_set_callback(nreq, req->base.flags,
NULL, NULL);
skcipher_request_set_crypt(nreq, req->src, req->dst,
req->assoclen + req->cryptlen,
NULL);
err = crypto_skcipher_encrypt(nreq);
if (err)
return err;
}
if (unlikely(!IS_ALIGNED((unsigned long)info,
crypto_aead_alignmask(geniv) + 1))) {
info = kmemdup(req->iv, ivsize, req->base.flags &
CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
GFP_ATOMIC);
if (!info)
return -ENOMEM;
compl = seqiv_aead_encrypt_complete;
data = req;
}
aead_request_set_callback(subreq, req->base.flags, compl, data);
aead_request_set_crypt(subreq, req->dst, req->dst,
req->cryptlen - ivsize, info);
aead_request_set_ad(subreq, req->assoclen + ivsize);
crypto_xor(info, ctx->salt, ivsize);
scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1);
err = crypto_aead_encrypt(subreq);
if (unlikely(info != req->iv))
seqiv_aead_encrypt_complete2(req, err);
return err;
}
static int seqiv_aead_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 = 8;
if (req->cryptlen < ivsize + crypto_aead_authsize(geniv))
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 seqiv_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))
goto free_inst;
inst->alg.encrypt = seqiv_aead_encrypt;
inst->alg.decrypt = seqiv_aead_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 seqiv_tmpl = {
.name = "seqiv",
.create = seqiv_aead_create,
.module = THIS_MODULE,
};
static int __init seqiv_module_init(void)
{
return crypto_register_template(&seqiv_tmpl);
}
static void __exit seqiv_module_exit(void)
{
crypto_unregister_template(&seqiv_tmpl);
}
subsys_initcall(seqiv_module_init);
module_exit(seqiv_module_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Sequence Number IV Generator");
MODULE_ALIAS_CRYPTO("seqiv");
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