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