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 || 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
  35 out:
  36         kfree_sensitive(subreq->iv);
  37 }
  38
  39 static 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
  47 static 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
 108 static 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
 135 static 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) {
 160 free_inst:
 161                 inst->free(inst);
 162         }
 163         return err;
 164 }
 165
 166 static struct crypto_template seqiv_tmpl = {
 167         .name = "seqiv",
 168         .create = seqiv_aead_create,
 169         .module = THIS_MODULE,
 170 };
 171
 172 static int __init seqiv_module_init(void)
 173 {
 174         return crypto_register_template(&seqiv_tmpl);
 175 }
 176
 177 static void __exit seqiv_module_exit(void)
 178 {
 179         crypto_unregister_template(&seqiv_tmpl);
 180 }
 181
 182 subsys_initcall(seqiv_module_init);
 183 module_exit(seqiv_module_exit);
 184
 185 MODULE_LICENSE("GPL");
 186 MODULE_DESCRIPTION("Sequence Number IV Generator");
 187 MODULE_ALIAS_CRYPTO("seqiv");