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/aead.h>
  17 #include <crypto/internal/skcipher.h>
  18 #include <crypto/rng.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/spinlock.h>
  25 #include <linux/string.h>
  26
  27 struct seqiv_ctx {
  28         spinlock_t lock;
  29         u8 salt[] __attribute__ ((aligned(__alignof__(u32))));
  30 };
  31
  32 static void seqiv_complete2(struct skcipher_givcrypt_request *req, int err)
  33 {
  34         struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
  35         struct crypto_ablkcipher *geniv;
  36
  37         if (err == -EINPROGRESS)
  38                 return;
  39
  40         if (err)
  41                 goto out;
  42
  43         geniv = skcipher_givcrypt_reqtfm(req);
  44         memcpy(req->creq.info, subreq->info, crypto_ablkcipher_ivsize(geniv));
  45
  46 out:
  47         kfree(subreq->info);
  48 }
  49
  50 static void seqiv_complete(struct crypto_async_request *base, int err)
  51 {
  52         struct skcipher_givcrypt_request *req = base->data;
  53
  54         seqiv_complete2(req, err);
  55         skcipher_givcrypt_complete(req, err);
  56 }
  57
  58 static void seqiv_aead_complete2(struct aead_givcrypt_request *req, int err)
  59 {
  60         struct aead_request *subreq = aead_givcrypt_reqctx(req);
  61         struct crypto_aead *geniv;
  62
  63         if (err == -EINPROGRESS)
  64                 return;
  65
  66         if (err)
  67                 goto out;
  68
  69         geniv = aead_givcrypt_reqtfm(req);
  70         memcpy(req->areq.iv, subreq->iv, crypto_aead_ivsize(geniv));
  71
  72 out:
  73         kfree(subreq->iv);
  74 }
  75
  76 static void seqiv_aead_complete(struct crypto_async_request *base, int err)
  77 {
  78         struct aead_givcrypt_request *req = base->data;
  79
  80         seqiv_aead_complete2(req, err);
  81         aead_givcrypt_complete(req, err);
  82 }
  83
  84 static void seqiv_geniv(struct seqiv_ctx *ctx, u8 *info, u64 seq,
  85                         unsigned int ivsize)
  86 {
  87         unsigned int len = ivsize;
  88
  89         if (ivsize > sizeof(u64)) {
  90                 memset(info, 0, ivsize - sizeof(u64));
  91                 len = sizeof(u64);
  92         }
  93         seq = cpu_to_be64(seq);
  94         memcpy(info + ivsize - len, &seq, len);
  95         crypto_xor(info, ctx->salt, ivsize);
  96 }
  97
  98 static int seqiv_givencrypt(struct skcipher_givcrypt_request *req)
  99 {
 100         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
 101         struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
 102         struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
 103         crypto_completion_t compl;
 104         void *data;
 105         u8 *info;
 106         unsigned int ivsize;
 107         int err;
 108
 109         ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
 110
 111         compl = req->creq.base.complete;
 112         data = req->creq.base.data;
 113         info = req->creq.info;
 114
 115         ivsize = crypto_ablkcipher_ivsize(geniv);
 116
 117         if (unlikely(!IS_ALIGNED((unsigned long)info,
 118                                  crypto_ablkcipher_alignmask(geniv) + 1))) {
 119                 info = kmalloc(ivsize, req->creq.base.flags &
 120                                        CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL:
 121                                                                   GFP_ATOMIC);
 122                 if (!info)
 123                         return -ENOMEM;
 124
 125                 compl = seqiv_complete;
 126                 data = req;
 127         }
 128
 129         ablkcipher_request_set_callback(subreq, req->creq.base.flags, compl,
 130                                         data);
 131         ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
 132                                      req->creq.nbytes, info);
 133
 134         seqiv_geniv(ctx, info, req->seq, ivsize);
 135         memcpy(req->giv, info, ivsize);
 136
 137         err = crypto_ablkcipher_encrypt(subreq);
 138         if (unlikely(info != req->creq.info))
 139                 seqiv_complete2(req, err);
 140         return err;
 141 }
 142
 143 static int seqiv_aead_givencrypt(struct aead_givcrypt_request *req)
 144 {
 145         struct crypto_aead *geniv = aead_givcrypt_reqtfm(req);
 146         struct seqiv_ctx *ctx = crypto_aead_ctx(geniv);
 147         struct aead_request *areq = &req->areq;
 148         struct aead_request *subreq = aead_givcrypt_reqctx(req);
 149         crypto_completion_t compl;
 150         void *data;
 151         u8 *info;
 152         unsigned int ivsize;
 153         int err;
 154
 155         aead_request_set_tfm(subreq, aead_geniv_base(geniv));
 156
 157         compl = areq->base.complete;
 158         data = areq->base.data;
 159         info = areq->iv;
 160
 161         ivsize = crypto_aead_ivsize(geniv);
 162
 163         if (unlikely(!IS_ALIGNED((unsigned long)info,
 164                                  crypto_aead_alignmask(geniv) + 1))) {
 165                 info = kmalloc(ivsize, areq->base.flags &
 166                                        CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL:
 167                                                                   GFP_ATOMIC);
 168                 if (!info)
 169                         return -ENOMEM;
 170
 171                 compl = seqiv_aead_complete;
 172                 data = req;
 173         }
 174
 175         aead_request_set_callback(subreq, areq->base.flags, compl, data);
 176         aead_request_set_crypt(subreq, areq->src, areq->dst, areq->cryptlen,
 177                                info);
 178         aead_request_set_assoc(subreq, areq->assoc, areq->assoclen);
 179
 180         seqiv_geniv(ctx, info, req->seq, ivsize);
 181         memcpy(req->giv, info, ivsize);
 182
 183         err = crypto_aead_encrypt(subreq);
 184         if (unlikely(info != areq->iv))
 185                 seqiv_aead_complete2(req, err);
 186         return err;
 187 }
 188
 189 static int seqiv_givencrypt_first(struct skcipher_givcrypt_request *req)
 190 {
 191         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
 192         struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
 193         int err = 0;
 194
 195         spin_lock_bh(&ctx->lock);
 196         if (crypto_ablkcipher_crt(geniv)->givencrypt != seqiv_givencrypt_first)
 197                 goto unlock;
 198
 199         crypto_ablkcipher_crt(geniv)->givencrypt = seqiv_givencrypt;
 200         err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt,
 201                                    crypto_ablkcipher_ivsize(geniv));
 202
 203 unlock:
 204         spin_unlock_bh(&ctx->lock);
 205
 206         if (err)
 207                 return err;
 208
 209         return seqiv_givencrypt(req);
 210 }
 211
 212 static int seqiv_aead_givencrypt_first(struct aead_givcrypt_request *req)
 213 {
 214         struct crypto_aead *geniv = aead_givcrypt_reqtfm(req);
 215         struct seqiv_ctx *ctx = crypto_aead_ctx(geniv);
 216         int err = 0;
 217
 218         spin_lock_bh(&ctx->lock);
 219         if (crypto_aead_crt(geniv)->givencrypt != seqiv_aead_givencrypt_first)
 220                 goto unlock;
 221
 222         crypto_aead_crt(geniv)->givencrypt = seqiv_aead_givencrypt;
 223         err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt,
 224                                    crypto_aead_ivsize(geniv));
 225
 226 unlock:
 227         spin_unlock_bh(&ctx->lock);
 228
 229         if (err)
 230                 return err;
 231
 232         return seqiv_aead_givencrypt(req);
 233 }
 234
 235 static int seqiv_init(struct crypto_tfm *tfm)
 236 {
 237         struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm);
 238         struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
 239
 240         spin_lock_init(&ctx->lock);
 241
 242         tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request);
 243
 244         return skcipher_geniv_init(tfm);
 245 }
 246
 247 static int seqiv_aead_init(struct crypto_tfm *tfm)
 248 {
 249         struct crypto_aead *geniv = __crypto_aead_cast(tfm);
 250         struct seqiv_ctx *ctx = crypto_aead_ctx(geniv);
 251
 252         spin_lock_init(&ctx->lock);
 253
 254         tfm->crt_aead.reqsize = sizeof(struct aead_request);
 255
 256         return aead_geniv_init(tfm);
 257 }
 258
 259 static struct crypto_template seqiv_tmpl;
 260
 261 static struct crypto_instance *seqiv_ablkcipher_alloc(struct rtattr **tb)
 262 {
 263         struct crypto_instance *inst;
 264
 265         inst = skcipher_geniv_alloc(&seqiv_tmpl, tb, 0, 0);
 266
 267         if (IS_ERR(inst))
 268                 goto out;
 269
 270         inst->alg.cra_ablkcipher.givencrypt = seqiv_givencrypt_first;
 271
 272         inst->alg.cra_init = seqiv_init;
 273         inst->alg.cra_exit = skcipher_geniv_exit;
 274
 275         inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize;
 276
 277 out:
 278         return inst;
 279 }
 280
 281 static struct crypto_instance *seqiv_aead_alloc(struct rtattr **tb)
 282 {
 283         struct crypto_instance *inst;
 284
 285         inst = aead_geniv_alloc(&seqiv_tmpl, tb, 0, 0);
 286
 287         if (IS_ERR(inst))
 288                 goto out;
 289
 290         inst->alg.cra_aead.givencrypt = seqiv_aead_givencrypt_first;
 291
 292         inst->alg.cra_init = seqiv_aead_init;
 293         inst->alg.cra_exit = aead_geniv_exit;
 294
 295         inst->alg.cra_ctxsize = inst->alg.cra_aead.ivsize;
 296
 297 out:
 298         return inst;
 299 }
 300
 301 static struct crypto_instance *seqiv_alloc(struct rtattr **tb)
 302 {
 303         struct crypto_attr_type *algt;
 304         struct crypto_instance *inst;
 305         int err;
 306
 307         algt = crypto_get_attr_type(tb);
 308         if (IS_ERR(algt))
 309                 return ERR_CAST(algt);
 310
 311         err = crypto_get_default_rng();
 312         if (err)
 313                 return ERR_PTR(err);
 314
 315         if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK)
 316                 inst = seqiv_ablkcipher_alloc(tb);
 317         else
 318                 inst = seqiv_aead_alloc(tb);
 319
 320         if (IS_ERR(inst))
 321                 goto put_rng;
 322
 323         inst->alg.cra_alignmask |= __alignof__(u32) - 1;
 324         inst->alg.cra_ctxsize += sizeof(struct seqiv_ctx);
 325
 326 out:
 327         return inst;
 328
 329 put_rng:
 330         crypto_put_default_rng();
 331         goto out;
 332 }
 333
 334 static void seqiv_free(struct crypto_instance *inst)
 335 {
 336         if ((inst->alg.cra_flags ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK)
 337                 skcipher_geniv_free(inst);
 338         else
 339                 aead_geniv_free(inst);
 340         crypto_put_default_rng();
 341 }
 342
 343 static struct crypto_template seqiv_tmpl = {
 344         .name = "seqiv",
 345         .alloc = seqiv_alloc,
 346         .free = seqiv_free,
 347         .module = THIS_MODULE,
 348 };
 349
 350 static int __init seqiv_module_init(void)
 351 {
 352         return crypto_register_template(&seqiv_tmpl);
 353 }
 354
 355 static void __exit seqiv_module_exit(void)
 356 {
 357         crypto_unregister_template(&seqiv_tmpl);
 358 }
 359
 360 module_init(seqiv_module_init);
 361 module_exit(seqiv_module_exit);
 362
 363 MODULE_LICENSE("GPL");
 364 MODULE_DESCRIPTION("Sequence Number IV Generator");
 365 MODULE_ALIAS_CRYPTO("seqiv");