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/internal/skcipher.h>
  18 #include <crypto/rng.h>
  19 #include <crypto/scatterwalk.h>
  20 #include <linux/err.h>
  21 #include <linux/init.h>
  22 #include <linux/kernel.h>
  23 #include <linux/module.h>
  24 #include <linux/slab.h>
  25 #include <linux/spinlock.h>
  26 #include <linux/string.h>
  27
  28 struct seqiv_ctx {
  29         spinlock_t lock;
  30         u8 salt[] __attribute__ ((aligned(__alignof__(u32))));
  31 };
  32
  33 static void seqiv_free(struct crypto_instance *inst);
  34
  35 static void seqiv_complete2(struct skcipher_givcrypt_request *req, int err)
  36 {
  37         struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
  38         struct crypto_ablkcipher *geniv;
  39
  40         if (err == -EINPROGRESS)
  41                 return;
  42
  43         if (err)
  44                 goto out;
  45
  46         geniv = skcipher_givcrypt_reqtfm(req);
  47         memcpy(req->creq.info, subreq->info, crypto_ablkcipher_ivsize(geniv));
  48
  49 out:
  50         kfree(subreq->info);
  51 }
  52
  53 static void seqiv_complete(struct crypto_async_request *base, int err)
  54 {
  55         struct skcipher_givcrypt_request *req = base->data;
  56
  57         seqiv_complete2(req, err);
  58         skcipher_givcrypt_complete(req, err);
  59 }
  60
  61 static void seqiv_aead_encrypt_complete2(struct aead_request *req, int err)
  62 {
  63         struct aead_request *subreq = aead_request_ctx(req);
  64         struct crypto_aead *geniv;
  65
  66         if (err == -EINPROGRESS)
  67                 return;
  68
  69         if (err)
  70                 goto out;
  71
  72         geniv = crypto_aead_reqtfm(req);
  73         memcpy(req->iv, subreq->iv, crypto_aead_ivsize(geniv));
  74
  75 out:
  76         kzfree(subreq->iv);
  77 }
  78
  79 static void seqiv_aead_encrypt_complete(struct crypto_async_request *base,
  80                                         int err)
  81 {
  82         struct aead_request *req = base->data;
  83
  84         seqiv_aead_encrypt_complete2(req, err);
  85         aead_request_complete(req, err);
  86 }
  87
  88 static void seqiv_geniv(struct seqiv_ctx *ctx, u8 *info, u64 seq,
  89                         unsigned int ivsize)
  90 {
  91         unsigned int len = ivsize;
  92
  93         if (ivsize > sizeof(u64)) {
  94                 memset(info, 0, ivsize - sizeof(u64));
  95                 len = sizeof(u64);
  96         }
  97         seq = cpu_to_be64(seq);
  98         memcpy(info + ivsize - len, &seq, len);
  99         crypto_xor(info, ctx->salt, ivsize);
 100 }
 101
 102 static int seqiv_givencrypt(struct skcipher_givcrypt_request *req)
 103 {
 104         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
 105         struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
 106         struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
 107         crypto_completion_t compl;
 108         void *data;
 109         u8 *info;
 110         unsigned int ivsize;
 111         int err;
 112
 113         ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
 114
 115         compl = req->creq.base.complete;
 116         data = req->creq.base.data;
 117         info = req->creq.info;
 118
 119         ivsize = crypto_ablkcipher_ivsize(geniv);
 120
 121         if (unlikely(!IS_ALIGNED((unsigned long)info,
 122                                  crypto_ablkcipher_alignmask(geniv) + 1))) {
 123                 info = kmalloc(ivsize, req->creq.base.flags &
 124                                        CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL:
 125                                                                   GFP_ATOMIC);
 126                 if (!info)
 127                         return -ENOMEM;
 128
 129                 compl = seqiv_complete;
 130                 data = req;
 131         }
 132
 133         ablkcipher_request_set_callback(subreq, req->creq.base.flags, compl,
 134                                         data);
 135         ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
 136                                      req->creq.nbytes, info);
 137
 138         seqiv_geniv(ctx, info, req->seq, ivsize);
 139         memcpy(req->giv, info, ivsize);
 140
 141         err = crypto_ablkcipher_encrypt(subreq);
 142         if (unlikely(info != req->creq.info))
 143                 seqiv_complete2(req, err);
 144         return err;
 145 }
 146
 147 static int seqiv_aead_encrypt(struct aead_request *req)
 148 {
 149         struct crypto_aead *geniv = crypto_aead_reqtfm(req);
 150         struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
 151         struct aead_request *subreq = aead_request_ctx(req);
 152         crypto_completion_t compl;
 153         void *data;
 154         u8 *info;
 155         unsigned int ivsize = 8;
 156         int err;
 157
 158         if (req->cryptlen < ivsize)
 159                 return -EINVAL;
 160
 161         aead_request_set_tfm(subreq, ctx->child);
 162
 163         compl = req->base.complete;
 164         data = req->base.data;
 165         info = req->iv;
 166
 167         if (req->src != req->dst) {
 168                 struct blkcipher_desc desc = {
 169                         .tfm = ctx->null,
 170                 };
 171
 172                 err = crypto_blkcipher_encrypt(&desc, req->dst, req->src,
 173                                                req->assoclen + req->cryptlen);
 174                 if (err)
 175                         return err;
 176         }
 177
 178         if (unlikely(!IS_ALIGNED((unsigned long)info,
 179                                  crypto_aead_alignmask(geniv) + 1))) {
 180                 info = kmalloc(ivsize, req->base.flags &
 181                                        CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL:
 182                                                                   GFP_ATOMIC);
 183                 if (!info)
 184                         return -ENOMEM;
 185
 186                 memcpy(info, req->iv, ivsize);
 187                 compl = seqiv_aead_encrypt_complete;
 188                 data = req;
 189         }
 190
 191         aead_request_set_callback(subreq, req->base.flags, compl, data);
 192         aead_request_set_crypt(subreq, req->dst, req->dst,
 193                                req->cryptlen - ivsize, info);
 194         aead_request_set_ad(subreq, req->assoclen + ivsize);
 195
 196         crypto_xor(info, ctx->salt, ivsize);
 197         scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1);
 198
 199         err = crypto_aead_encrypt(subreq);
 200         if (unlikely(info != req->iv))
 201                 seqiv_aead_encrypt_complete2(req, err);
 202         return err;
 203 }
 204
 205 static int seqiv_aead_decrypt(struct aead_request *req)
 206 {
 207         struct crypto_aead *geniv = crypto_aead_reqtfm(req);
 208         struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
 209         struct aead_request *subreq = aead_request_ctx(req);
 210         crypto_completion_t compl;
 211         void *data;
 212         unsigned int ivsize = 8;
 213
 214         if (req->cryptlen < ivsize + crypto_aead_authsize(geniv))
 215                 return -EINVAL;
 216
 217         aead_request_set_tfm(subreq, ctx->child);
 218
 219         compl = req->base.complete;
 220         data = req->base.data;
 221
 222         aead_request_set_callback(subreq, req->base.flags, compl, data);
 223         aead_request_set_crypt(subreq, req->src, req->dst,
 224                                req->cryptlen - ivsize, req->iv);
 225         aead_request_set_ad(subreq, req->assoclen + ivsize);
 226
 227         scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);
 228
 229         return crypto_aead_decrypt(subreq);
 230 }
 231
 232 static int seqiv_init(struct crypto_tfm *tfm)
 233 {
 234         struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm);
 235         struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
 236         int err;
 237
 238         spin_lock_init(&ctx->lock);
 239
 240         tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request);
 241
 242         err = 0;
 243         if (!crypto_get_default_rng()) {
 244                 crypto_ablkcipher_crt(geniv)->givencrypt = seqiv_givencrypt;
 245                 err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt,
 246                                            crypto_ablkcipher_ivsize(geniv));
 247                 crypto_put_default_rng();
 248         }
 249
 250         return err ?: skcipher_geniv_init(tfm);
 251 }
 252
 253 static int seqiv_ablkcipher_create(struct crypto_template *tmpl,
 254                                    struct rtattr **tb)
 255 {
 256         struct crypto_instance *inst;
 257         int err;
 258
 259         inst = skcipher_geniv_alloc(tmpl, tb, 0, 0);
 260
 261         if (IS_ERR(inst))
 262                 return PTR_ERR(inst);
 263
 264         err = -EINVAL;
 265         if (inst->alg.cra_ablkcipher.ivsize < sizeof(u64))
 266                 goto free_inst;
 267
 268         inst->alg.cra_init = seqiv_init;
 269         inst->alg.cra_exit = skcipher_geniv_exit;
 270
 271         inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize;
 272         inst->alg.cra_ctxsize += sizeof(struct seqiv_ctx);
 273
 274         inst->alg.cra_alignmask |= __alignof__(u32) - 1;
 275
 276         err = crypto_register_instance(tmpl, inst);
 277         if (err)
 278                 goto free_inst;
 279
 280 out:
 281         return err;
 282
 283 free_inst:
 284         skcipher_geniv_free(inst);
 285         goto out;
 286 }
 287
 288 static int seqiv_aead_create(struct crypto_template *tmpl, struct rtattr **tb)
 289 {
 290         struct aead_instance *inst;
 291         struct crypto_aead_spawn *spawn;
 292         struct aead_alg *alg;
 293         int err;
 294
 295         inst = aead_geniv_alloc(tmpl, tb, 0, 0);
 296
 297         if (IS_ERR(inst))
 298                 return PTR_ERR(inst);
 299
 300         inst->alg.base.cra_alignmask |= __alignof__(u32) - 1;
 301
 302         spawn = aead_instance_ctx(inst);
 303         alg = crypto_spawn_aead_alg(spawn);
 304
 305         err = -EINVAL;
 306         if (inst->alg.ivsize != sizeof(u64))
 307                 goto free_inst;
 308
 309         inst->alg.encrypt = seqiv_aead_encrypt;
 310         inst->alg.decrypt = seqiv_aead_decrypt;
 311
 312         inst->alg.init = aead_init_geniv;
 313         inst->alg.exit = aead_exit_geniv;
 314
 315         inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx);
 316         inst->alg.base.cra_ctxsize += inst->alg.ivsize;
 317
 318         err = aead_register_instance(tmpl, inst);
 319         if (err)
 320                 goto free_inst;
 321
 322 out:
 323         return err;
 324
 325 free_inst:
 326         aead_geniv_free(inst);
 327         goto out;
 328 }
 329
 330 static int seqiv_create(struct crypto_template *tmpl, struct rtattr **tb)
 331 {
 332         struct crypto_attr_type *algt;
 333         int err;
 334
 335         algt = crypto_get_attr_type(tb);
 336         if (IS_ERR(algt))
 337                 return PTR_ERR(algt);
 338
 339         if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK)
 340                 err = seqiv_ablkcipher_create(tmpl, tb);
 341         else
 342                 err = seqiv_aead_create(tmpl, tb);
 343
 344         return err;
 345 }
 346
 347 static void seqiv_free(struct crypto_instance *inst)
 348 {
 349         if ((inst->alg.cra_flags ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK)
 350                 skcipher_geniv_free(inst);
 351         else
 352                 aead_geniv_free(aead_instance(inst));
 353 }
 354
 355 static struct crypto_template seqiv_tmpl = {
 356         .name = "seqiv",
 357         .create = seqiv_create,
 358         .free = seqiv_free,
 359         .module = THIS_MODULE,
 360 };
 361
 362 static int __init seqiv_module_init(void)
 363 {
 364         return crypto_register_template(&seqiv_tmpl);
 365 }
 366
 367 static void __exit seqiv_module_exit(void)
 368 {
 369         crypto_unregister_template(&seqiv_tmpl);
 370 }
 371
 372 module_init(seqiv_module_init);
 373 module_exit(seqiv_module_exit);
 374
 375 MODULE_LICENSE("GPL");
 376 MODULE_DESCRIPTION("Sequence Number IV Generator");
 377 MODULE_ALIAS_CRYPTO("seqiv");