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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * seqiv: Sequence Number IV Generator4 *5 * This generator generates an IV based on a sequence number by xoring it6 * with a salt. This algorithm is mainly useful for CTR and similar modes.7 *8 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>9 */10 11#include <crypto/internal/geniv.h>12#include <crypto/scatterwalk.h>13#include <crypto/skcipher.h>14#include <linux/err.h>15#include <linux/init.h>16#include <linux/kernel.h>17#include <linux/module.h>18#include <linux/slab.h>19#include <linux/string.h>20 21static void seqiv_aead_encrypt_complete2(struct aead_request *req, int err)22{23 struct aead_request *subreq = aead_request_ctx(req);24 struct crypto_aead *geniv;25 26 if (err == -EINPROGRESS || err == -EBUSY)27 return;28 29 if (err)30 goto out;31 32 geniv = crypto_aead_reqtfm(req);33 memcpy(req->iv, subreq->iv, crypto_aead_ivsize(geniv));34 35out:36 kfree_sensitive(subreq->iv);37}38 39static void seqiv_aead_encrypt_complete(void *data, int err)40{41 struct aead_request *req = data;42 43 seqiv_aead_encrypt_complete2(req, err);44 aead_request_complete(req, err);45}46 47static int seqiv_aead_encrypt(struct aead_request *req)48{49 struct crypto_aead *geniv = crypto_aead_reqtfm(req);50 struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);51 struct aead_request *subreq = aead_request_ctx(req);52 crypto_completion_t compl;53 void *data;54 u8 *info;55 unsigned int ivsize = 8;56 int err;57 58 if (req->cryptlen < ivsize)59 return -EINVAL;60 61 aead_request_set_tfm(subreq, ctx->child);62 63 compl = req->base.complete;64 data = req->base.data;65 info = req->iv;66 67 if (req->src != req->dst) {68 SYNC_SKCIPHER_REQUEST_ON_STACK(nreq, ctx->sknull);69 70 skcipher_request_set_sync_tfm(nreq, ctx->sknull);71 skcipher_request_set_callback(nreq, req->base.flags,72 NULL, NULL);73 skcipher_request_set_crypt(nreq, req->src, req->dst,74 req->assoclen + req->cryptlen,75 NULL);76 77 err = crypto_skcipher_encrypt(nreq);78 if (err)79 return err;80 }81 82 if (unlikely(!IS_ALIGNED((unsigned long)info,83 crypto_aead_alignmask(geniv) + 1))) {84 info = kmemdup(req->iv, ivsize, req->base.flags &85 CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :86 GFP_ATOMIC);87 if (!info)88 return -ENOMEM;89 90 compl = seqiv_aead_encrypt_complete;91 data = req;92 }93 94 aead_request_set_callback(subreq, req->base.flags, compl, data);95 aead_request_set_crypt(subreq, req->dst, req->dst,96 req->cryptlen - ivsize, info);97 aead_request_set_ad(subreq, req->assoclen + ivsize);98 99 crypto_xor(info, ctx->salt, ivsize);100 scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1);101 102 err = crypto_aead_encrypt(subreq);103 if (unlikely(info != req->iv))104 seqiv_aead_encrypt_complete2(req, err);105 return err;106}107 108static int seqiv_aead_decrypt(struct aead_request *req)109{110 struct crypto_aead *geniv = crypto_aead_reqtfm(req);111 struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);112 struct aead_request *subreq = aead_request_ctx(req);113 crypto_completion_t compl;114 void *data;115 unsigned int ivsize = 8;116 117 if (req->cryptlen < ivsize + crypto_aead_authsize(geniv))118 return -EINVAL;119 120 aead_request_set_tfm(subreq, ctx->child);121 122 compl = req->base.complete;123 data = req->base.data;124 125 aead_request_set_callback(subreq, req->base.flags, compl, data);126 aead_request_set_crypt(subreq, req->src, req->dst,127 req->cryptlen - ivsize, req->iv);128 aead_request_set_ad(subreq, req->assoclen + ivsize);129 130 scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);131 132 return crypto_aead_decrypt(subreq);133}134 135static int seqiv_aead_create(struct crypto_template *tmpl, struct rtattr **tb)136{137 struct aead_instance *inst;138 int err;139 140 inst = aead_geniv_alloc(tmpl, tb);141 142 if (IS_ERR(inst))143 return PTR_ERR(inst);144 145 err = -EINVAL;146 if (inst->alg.ivsize != sizeof(u64))147 goto free_inst;148 149 inst->alg.encrypt = seqiv_aead_encrypt;150 inst->alg.decrypt = seqiv_aead_decrypt;151 152 inst->alg.init = aead_init_geniv;153 inst->alg.exit = aead_exit_geniv;154 155 inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx);156 inst->alg.base.cra_ctxsize += inst->alg.ivsize;157 158 err = aead_register_instance(tmpl, inst);159 if (err) {160free_inst:161 inst->free(inst);162 }163 return err;164}165 166static struct crypto_template seqiv_tmpl = {167 .name = "seqiv",168 .create = seqiv_aead_create,169 .module = THIS_MODULE,170};171 172static int __init seqiv_module_init(void)173{174 return crypto_register_template(&seqiv_tmpl);175}176 177static void __exit seqiv_module_exit(void)178{179 crypto_unregister_template(&seqiv_tmpl);180}181 182subsys_initcall(seqiv_module_init);183module_exit(seqiv_module_exit);184 185MODULE_LICENSE("GPL");186MODULE_DESCRIPTION("Sequence Number IV Generator");187MODULE_ALIAS_CRYPTO("seqiv");188