crypto/seqiv.c

   1 /*
   2  * seqiv: Sequence Number IV Generator
   3  *
   4  * This generator generates an IV based on a sequence number by xoring it
   5  * with a salt.  This algorithm is mainly useful for CTR and similar modes.
   6  *
   7  * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU General Public License as published by the Free
  11  * Software Foundation; either version 2 of the License, or (at your option)
  12  * any later version.
  13  *
  14  */
  15
  16 #include <crypto/internal/geniv.h>
  17 #include <crypto/scatterwalk.h>
  18 #include <crypto/skcipher.h>
  19 #include <linux/err.h>
  20 #include <linux/init.h>
  21 #include <linux/kernel.h>
  22 #include <linux/module.h>
  23 #include <linux/slab.h>
  24 #include <linux/string.h>
  25
  26 static void seqiv_free(struct crypto_instance *inst);
  27
  28 static void seqiv_aead_encrypt_complete2(struct aead_request *req, int err)
  29 {
  30         struct aead_request *subreq = aead_request_ctx(req);
  31         struct crypto_aead *geniv;
  32
  33         if (err == -EINPROGRESS)
  34                 return;
  35
  36         if (err)
  37                 goto out;
  38
  39         geniv = crypto_aead_reqtfm(req);
  40         memcpy(req->iv, subreq->iv, crypto_aead_ivsize(geniv));
  41
  42 out:
  43         kzfree(subreq->iv);
  44 }
  45
  46 static void seqiv_aead_encrypt_complete(struct crypto_async_request *base,
  47                                         int err)
  48 {
  49         struct aead_request *req = base->data;
  50
  51         seqiv_aead_encrypt_complete2(req, err);
  52         aead_request_complete(req, err);
  53 }
  54
  55 static int seqiv_aead_encrypt(struct aead_request *req)
  56 {
  57         struct crypto_aead *geniv = crypto_aead_reqtfm(req);
  58         struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
  59         struct aead_request *subreq = aead_request_ctx(req);
  60         crypto_completion_t compl;
  61         void *data;
  62         u8 *info;
  63         unsigned int ivsize = 8;
  64         int err;
  65
  66         if (req->cryptlen < ivsize)
  67                 return -EINVAL;
  68
  69         aead_request_set_tfm(subreq, ctx->child);
  70
  71         compl = req->base.complete;
  72         data = req->base.data;
  73         info = req->iv;
  74
  75         if (req->src != req->dst) {
  76                 SKCIPHER_REQUEST_ON_STACK(nreq, ctx->sknull);
  77
  78                 skcipher_request_set_tfm(nreq, ctx->sknull);
  79                 skcipher_request_set_callback(nreq, req->base.flags,
  80                                               NULL, NULL);
  81                 skcipher_request_set_crypt(nreq, req->src, req->dst,
  82                                            req->assoclen + req->cryptlen,
  83                                            NULL);
  84
  85                 err = crypto_skcipher_encrypt(nreq);
  86                 if (err)
  87                         return err;
  88         }
  89
  90         if (unlikely(!IS_ALIGNED((unsigned long)info,
  91                                  crypto_aead_alignmask(geniv) + 1))) {
  92                 info = kmalloc(ivsize, req->base.flags &
  93                                        CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL:
  94                                                                   GFP_ATOMIC);
  95                 if (!info)
  96                         return -ENOMEM;
  97
  98                 memcpy(info, req->iv, ivsize);
  99                 compl = seqiv_aead_encrypt_complete;
 100                 data = req;
 101         }
 102
 103         aead_request_set_callback(subreq, req->base.flags, compl, data);
 104         aead_request_set_crypt(subreq, req->dst, req->dst,
 105                                req->cryptlen - ivsize, info);
 106         aead_request_set_ad(subreq, req->assoclen + ivsize);
 107
 108         crypto_xor(info, ctx->salt, ivsize);
 109         scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1);
 110
 111         err = crypto_aead_encrypt(subreq);
 112         if (unlikely(info != req->iv))
 113                 seqiv_aead_encrypt_complete2(req, err);
 114         return err;
 115 }
 116
 117 static int seqiv_aead_decrypt(struct aead_request *req)
 118 {
 119         struct crypto_aead *geniv = crypto_aead_reqtfm(req);
 120         struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
 121         struct aead_request *subreq = aead_request_ctx(req);
 122         crypto_completion_t compl;
 123         void *data;
 124         unsigned int ivsize = 8;
 125
 126         if (req->cryptlen < ivsize + crypto_aead_authsize(geniv))
 127                 return -EINVAL;
 128
 129         aead_request_set_tfm(subreq, ctx->child);
 130
 131         compl = req->base.complete;
 132         data = req->base.data;
 133
 134         aead_request_set_callback(subreq, req->base.flags, compl, data);
 135         aead_request_set_crypt(subreq, req->src, req->dst,
 136                                req->cryptlen - ivsize, req->iv);
 137         aead_request_set_ad(subreq, req->assoclen + ivsize);
 138
 139         scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);
 140
 141         return crypto_aead_decrypt(subreq);
 142 }
 143
 144 static int seqiv_aead_create(struct crypto_template *tmpl, struct rtattr **tb)
 145 {
 146         struct aead_instance *inst;
 147         int err;
 148
 149         inst = aead_geniv_alloc(tmpl, tb, 0, 0);
 150
 151         if (IS_ERR(inst))
 152                 return PTR_ERR(inst);
 153
 154         err = -EINVAL;
 155         if (inst->alg.ivsize != sizeof(u64))
 156                 goto free_inst;
 157
 158         inst->alg.encrypt = seqiv_aead_encrypt;
 159         inst->alg.decrypt = seqiv_aead_decrypt;
 160
 161         inst->alg.init = aead_init_geniv;
 162         inst->alg.exit = aead_exit_geniv;
 163
 164         inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx);
 165         inst->alg.base.cra_ctxsize += inst->alg.ivsize;
 166
 167         err = aead_register_instance(tmpl, inst);
 168         if (err)
 169                 goto free_inst;
 170
 171 out:
 172         return err;
 173
 174 free_inst:
 175         aead_geniv_free(inst);
 176         goto out;
 177 }
 178
 179 static int seqiv_create(struct crypto_template *tmpl, struct rtattr **tb)
 180 {
 181         struct crypto_attr_type *algt;
 182
 183         algt = crypto_get_attr_type(tb);
 184         if (IS_ERR(algt))
 185                 return PTR_ERR(algt);
 186
 187         if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK)
 188                 return -EINVAL;
 189
 190         return seqiv_aead_create(tmpl, tb);
 191 }
 192
 193 static void seqiv_free(struct crypto_instance *inst)
 194 {
 195         aead_geniv_free(aead_instance(inst));
 196 }
 197
 198 static struct crypto_template seqiv_tmpl = {
 199         .name = "seqiv",
 200         .create = seqiv_create,
 201         .free = seqiv_free,
 202         .module = THIS_MODULE,
 203 };
 204
 205 static int __init seqiv_module_init(void)
 206 {
 207         return crypto_register_template(&seqiv_tmpl);
 208 }
 209
 210 static void __exit seqiv_module_exit(void)
 211 {
 212         crypto_unregister_template(&seqiv_tmpl);
 213 }
 214
 215 module_init(seqiv_module_init);
 216 module_exit(seqiv_module_exit);
 217
 218 MODULE_LICENSE("GPL");
 219 MODULE_DESCRIPTION("Sequence Number IV Generator");
 220 MODULE_ALIAS_CRYPTO("seqiv");