crypto/seqiv.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * seqiv: Sequence Number IV Generator
   4  *
   5  * This generator generates an IV based on a sequence number by xoring it
   6  * 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
  21 static 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)
  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
  35 out:
  36         kfree_sensitive(subreq->iv);
  37 }
  38
  39 static void seqiv_aead_encrypt_complete(struct crypto_async_request *base,
  40                                         int err)
  41 {
  42         struct aead_request *req = base->data;
  43
  44         seqiv_aead_encrypt_complete2(req, err);
  45         aead_request_complete(req, err);
  46 }
  47
  48 static int seqiv_aead_encrypt(struct aead_request *req)
  49 {
  50         struct crypto_aead *geniv = crypto_aead_reqtfm(req);
  51         struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
  52         struct aead_request *subreq = aead_request_ctx(req);
  53         crypto_completion_t compl;
  54         void *data;
  55         u8 *info;
  56         unsigned int ivsize = 8;
  57         int err;
  58
  59         if (req->cryptlen < ivsize)
  60                 return -EINVAL;
  61
  62         aead_request_set_tfm(subreq, ctx->child);
  63
  64         compl = req->base.complete;
  65         data = req->base.data;
  66         info = req->iv;
  67
  68         if (req->src != req->dst) {
  69                 SYNC_SKCIPHER_REQUEST_ON_STACK(nreq, ctx->sknull);
  70
  71                 skcipher_request_set_sync_tfm(nreq, ctx->sknull);
  72                 skcipher_request_set_callback(nreq, req->base.flags,
  73                                               NULL, NULL);
  74                 skcipher_request_set_crypt(nreq, req->src, req->dst,
  75                                            req->assoclen + req->cryptlen,
  76                                            NULL);
  77
  78                 err = crypto_skcipher_encrypt(nreq);
  79                 if (err)
  80                         return err;
  81         }
  82
  83         if (unlikely(!IS_ALIGNED((unsigned long)info,
  84                                  crypto_aead_alignmask(geniv) + 1))) {
  85                 info = kmemdup(req->iv, ivsize, req->base.flags &
  86                                CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
  87                                GFP_ATOMIC);
  88                 if (!info)
  89                         return -ENOMEM;
  90
  91                 compl = seqiv_aead_encrypt_complete;
  92                 data = req;
  93         }
  94
  95         aead_request_set_callback(subreq, req->base.flags, compl, data);
  96         aead_request_set_crypt(subreq, req->dst, req->dst,
  97                                req->cryptlen - ivsize, info);
  98         aead_request_set_ad(subreq, req->assoclen + ivsize);
  99
 100         crypto_xor(info, ctx->salt, ivsize);
 101         scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1);
 102
 103         err = crypto_aead_encrypt(subreq);
 104         if (unlikely(info != req->iv))
 105                 seqiv_aead_encrypt_complete2(req, err);
 106         return err;
 107 }
 108
 109 static int seqiv_aead_decrypt(struct aead_request *req)
 110 {
 111         struct crypto_aead *geniv = crypto_aead_reqtfm(req);
 112         struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
 113         struct aead_request *subreq = aead_request_ctx(req);
 114         crypto_completion_t compl;
 115         void *data;
 116         unsigned int ivsize = 8;
 117
 118         if (req->cryptlen < ivsize + crypto_aead_authsize(geniv))
 119                 return -EINVAL;
 120
 121         aead_request_set_tfm(subreq, ctx->child);
 122
 123         compl = req->base.complete;
 124         data = req->base.data;
 125
 126         aead_request_set_callback(subreq, req->base.flags, compl, data);
 127         aead_request_set_crypt(subreq, req->src, req->dst,
 128                                req->cryptlen - ivsize, req->iv);
 129         aead_request_set_ad(subreq, req->assoclen + ivsize);
 130
 131         scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);
 132
 133         return crypto_aead_decrypt(subreq);
 134 }
 135
 136 static int seqiv_aead_create(struct crypto_template *tmpl, struct rtattr **tb)
 137 {
 138         struct aead_instance *inst;
 139         int err;
 140
 141         inst = aead_geniv_alloc(tmpl, tb);
 142
 143         if (IS_ERR(inst))
 144                 return PTR_ERR(inst);
 145
 146         err = -EINVAL;
 147         if (inst->alg.ivsize != sizeof(u64))
 148                 goto free_inst;
 149
 150         inst->alg.encrypt = seqiv_aead_encrypt;
 151         inst->alg.decrypt = seqiv_aead_decrypt;
 152
 153         inst->alg.init = aead_init_geniv;
 154         inst->alg.exit = aead_exit_geniv;
 155
 156         inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx);
 157         inst->alg.base.cra_ctxsize += inst->alg.ivsize;
 158
 159         err = aead_register_instance(tmpl, inst);
 160         if (err) {
 161 free_inst:
 162                 inst->free(inst);
 163         }
 164         return err;
 165 }
 166
 167 static struct crypto_template seqiv_tmpl = {
 168         .name = "seqiv",
 169         .create = seqiv_aead_create,
 170         .module = THIS_MODULE,
 171 };
 172
 173 static int __init seqiv_module_init(void)
 174 {
 175         return crypto_register_template(&seqiv_tmpl);
 176 }
 177
 178 static void __exit seqiv_module_exit(void)
 179 {
 180         crypto_unregister_template(&seqiv_tmpl);
 181 }
 182
 183 subsys_initcall(seqiv_module_init);
 184 module_exit(seqiv_module_exit);
 185
 186 MODULE_LICENSE("GPL");
 187 MODULE_DESCRIPTION("Sequence Number IV Generator");
 188 MODULE_ALIAS_CRYPTO("seqiv");