linux/crypto/seqiv.c
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   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
  26struct seqiv_ctx {
  27        spinlock_t lock;
  28        u8 salt[] __attribute__ ((aligned(__alignof__(u32))));
  29};
  30
  31static 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
  45out:
  46        kfree(subreq->info);
  47}
  48
  49static 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
  57static 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
  71out:
  72        kfree(subreq->iv);
  73}
  74
  75static 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
  83static 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
  97static 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
 142static 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
 188static 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
 202unlock:
 203        spin_unlock_bh(&ctx->lock);
 204
 205        if (err)
 206                return err;
 207
 208        return seqiv_givencrypt(req);
 209}
 210
 211static 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
 225unlock:
 226        spin_unlock_bh(&ctx->lock);
 227
 228        if (err)
 229                return err;
 230
 231        return seqiv_aead_givencrypt(req);
 232}
 233
 234static 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
 246static 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
 258static struct crypto_template seqiv_tmpl;
 259
 260static 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
 276out:
 277        return inst;
 278}
 279
 280static 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
 296out:
 297        return inst;
 298}
 299
 300static 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
 326out:
 327        return inst;
 328
 329put_rng:
 330        crypto_put_default_rng();
 331        goto out;
 332}
 333
 334static 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
 343static struct crypto_template seqiv_tmpl = {
 344        .name = "seqiv",
 345        .alloc = seqiv_alloc,
 346        .free = seqiv_free,
 347        .module = THIS_MODULE,
 348};
 349
 350static int __init seqiv_module_init(void)
 351{
 352        return crypto_register_template(&seqiv_tmpl);
 353}
 354
 355static void __exit seqiv_module_exit(void)
 356{
 357        crypto_unregister_template(&seqiv_tmpl);
 358}
 359
 360module_init(seqiv_module_init);
 361module_exit(seqiv_module_exit);
 362
 363MODULE_LICENSE("GPL");
 364MODULE_DESCRIPTION("Sequence Number IV Generator");
 365
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