root/crypto/essiv.c

DEFINITIONS

1. essiv_skcipher_setkey
2. essiv_aead_setkey
3. essiv_aead_setauthsize
4. essiv_skcipher_done
5. essiv_skcipher_crypt
6. essiv_skcipher_encrypt
7. essiv_skcipher_decrypt
8. essiv_aead_done
9. essiv_aead_crypt
10. essiv_aead_encrypt
11. essiv_aead_decrypt
12. essiv_init_tfm
13. essiv_skcipher_init_tfm
14. essiv_aead_init_tfm
15. essiv_skcipher_exit_tfm
16. essiv_aead_exit_tfm
17. essiv_skcipher_free_instance
18. essiv_aead_free_instance
19. parse_cipher_name
20. essiv_supported_algorithms
21. essiv_create
22. essiv_module_init
23. essiv_module_exit

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * ESSIV skcipher and aead template for block encryption
   4  *
   5  * This template encapsulates the ESSIV IV generation algorithm used by
   6  * dm-crypt and fscrypt, which converts the initial vector for the skcipher
   7  * used for block encryption, by encrypting it using the hash of the
   8  * skcipher key as encryption key. Usually, the input IV is a 64-bit sector
   9  * number in LE representation zero-padded to the size of the IV, but this
  10  * is not assumed by this driver.
  11  *
  12  * The typical use of this template is to instantiate the skcipher
  13  * 'essiv(cbc(aes),sha256)', which is the only instantiation used by
  14  * fscrypt, and the most relevant one for dm-crypt. However, dm-crypt
  15  * also permits ESSIV to be used in combination with the authenc template,
  16  * e.g., 'essiv(authenc(hmac(sha256),cbc(aes)),sha256)', in which case
  17  * we need to instantiate an aead that accepts the same special key format
  18  * as the authenc template, and deals with the way the encrypted IV is
  19  * embedded into the AAD area of the aead request. This means the AEAD
  20  * flavor produced by this template is tightly coupled to the way dm-crypt
  21  * happens to use it.
  22  *
  23  * Copyright (c) 2019 Linaro, Ltd. <ard.biesheuvel@linaro.org>
  24  *
  25  * Heavily based on:
  26  * adiantum length-preserving encryption mode
  27  *
  28  * Copyright 2018 Google LLC
  29  */
  30 
  31 #include <crypto/authenc.h>
  32 #include <crypto/internal/aead.h>
  33 #include <crypto/internal/hash.h>
  34 #include <crypto/internal/skcipher.h>
  35 #include <crypto/scatterwalk.h>
  36 #include <linux/module.h>
  37 
  38 #include "internal.h"
  39 
  40 struct essiv_instance_ctx {
  41         union {
  42                 struct crypto_skcipher_spawn    skcipher_spawn;
  43                 struct crypto_aead_spawn        aead_spawn;
  44         } u;
  45         char    essiv_cipher_name[CRYPTO_MAX_ALG_NAME];
  46         char    shash_driver_name[CRYPTO_MAX_ALG_NAME];
  47 };
  48 
  49 struct essiv_tfm_ctx {
  50         union {
  51                 struct crypto_skcipher  *skcipher;
  52                 struct crypto_aead      *aead;
  53         } u;
  54         struct crypto_cipher            *essiv_cipher;
  55         struct crypto_shash             *hash;
  56         int                             ivoffset;
  57 };
  58 
  59 struct essiv_aead_request_ctx {
  60         struct scatterlist              sg[4];
  61         u8                              *assoc;
  62         struct aead_request             aead_req;
  63 };
  64 
  65 static int essiv_skcipher_setkey(struct crypto_skcipher *tfm,
  66                                  const u8 *key, unsigned int keylen)
  67 {
  68         struct essiv_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
  69         SHASH_DESC_ON_STACK(desc, tctx->hash);
  70         u8 salt[HASH_MAX_DIGESTSIZE];
  71         int err;
  72 
  73         crypto_skcipher_clear_flags(tctx->u.skcipher, CRYPTO_TFM_REQ_MASK);
  74         crypto_skcipher_set_flags(tctx->u.skcipher,
  75                                   crypto_skcipher_get_flags(tfm) &
  76                                   CRYPTO_TFM_REQ_MASK);
  77         err = crypto_skcipher_setkey(tctx->u.skcipher, key, keylen);
  78         crypto_skcipher_set_flags(tfm,
  79                                   crypto_skcipher_get_flags(tctx->u.skcipher) &
  80                                   CRYPTO_TFM_RES_MASK);
  81         if (err)
  82                 return err;
  83 
  84         desc->tfm = tctx->hash;
  85         err = crypto_shash_digest(desc, key, keylen, salt);
  86         if (err)
  87                 return err;
  88 
  89         crypto_cipher_clear_flags(tctx->essiv_cipher, CRYPTO_TFM_REQ_MASK);
  90         crypto_cipher_set_flags(tctx->essiv_cipher,
  91                                 crypto_skcipher_get_flags(tfm) &
  92                                 CRYPTO_TFM_REQ_MASK);
  93         err = crypto_cipher_setkey(tctx->essiv_cipher, salt,
  94                                    crypto_shash_digestsize(tctx->hash));
  95         crypto_skcipher_set_flags(tfm,
  96                                   crypto_cipher_get_flags(tctx->essiv_cipher) &
  97                                   CRYPTO_TFM_RES_MASK);
  98 
  99         return err;
 100 }
 101 
 102 static int essiv_aead_setkey(struct crypto_aead *tfm, const u8 *key,
 103                              unsigned int keylen)
 104 {
 105         struct essiv_tfm_ctx *tctx = crypto_aead_ctx(tfm);
 106         SHASH_DESC_ON_STACK(desc, tctx->hash);
 107         struct crypto_authenc_keys keys;
 108         u8 salt[HASH_MAX_DIGESTSIZE];
 109         int err;
 110 
 111         crypto_aead_clear_flags(tctx->u.aead, CRYPTO_TFM_REQ_MASK);
 112         crypto_aead_set_flags(tctx->u.aead, crypto_aead_get_flags(tfm) &
 113                                             CRYPTO_TFM_REQ_MASK);
 114         err = crypto_aead_setkey(tctx->u.aead, key, keylen);
 115         crypto_aead_set_flags(tfm, crypto_aead_get_flags(tctx->u.aead) &
 116                                    CRYPTO_TFM_RES_MASK);
 117         if (err)
 118                 return err;
 119 
 120         if (crypto_authenc_extractkeys(&keys, key, keylen) != 0) {
 121                 crypto_aead_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
 122                 return -EINVAL;
 123         }
 124 
 125         desc->tfm = tctx->hash;
 126         err = crypto_shash_init(desc) ?:
 127               crypto_shash_update(desc, keys.enckey, keys.enckeylen) ?:
 128               crypto_shash_finup(desc, keys.authkey, keys.authkeylen, salt);
 129         if (err)
 130                 return err;
 131 
 132         crypto_cipher_clear_flags(tctx->essiv_cipher, CRYPTO_TFM_REQ_MASK);
 133         crypto_cipher_set_flags(tctx->essiv_cipher, crypto_aead_get_flags(tfm) &
 134                                                     CRYPTO_TFM_REQ_MASK);
 135         err = crypto_cipher_setkey(tctx->essiv_cipher, salt,
 136                                    crypto_shash_digestsize(tctx->hash));
 137         crypto_aead_set_flags(tfm, crypto_cipher_get_flags(tctx->essiv_cipher) &
 138                                    CRYPTO_TFM_RES_MASK);
 139 
 140         return err;
 141 }
 142 
 143 static int essiv_aead_setauthsize(struct crypto_aead *tfm,
 144                                   unsigned int authsize)
 145 {
 146         struct essiv_tfm_ctx *tctx = crypto_aead_ctx(tfm);
 147 
 148         return crypto_aead_setauthsize(tctx->u.aead, authsize);
 149 }
 150 
 151 static void essiv_skcipher_done(struct crypto_async_request *areq, int err)
 152 {
 153         struct skcipher_request *req = areq->data;
 154 
 155         skcipher_request_complete(req, err);
 156 }
 157 
 158 static int essiv_skcipher_crypt(struct skcipher_request *req, bool enc)
 159 {
 160         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 161         const struct essiv_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
 162         struct skcipher_request *subreq = skcipher_request_ctx(req);
 163 
 164         crypto_cipher_encrypt_one(tctx->essiv_cipher, req->iv, req->iv);
 165 
 166         skcipher_request_set_tfm(subreq, tctx->u.skcipher);
 167         skcipher_request_set_crypt(subreq, req->src, req->dst, req->cryptlen,
 168                                    req->iv);
 169         skcipher_request_set_callback(subreq, skcipher_request_flags(req),
 170                                       essiv_skcipher_done, req);
 171 
 172         return enc ? crypto_skcipher_encrypt(subreq) :
 173                      crypto_skcipher_decrypt(subreq);
 174 }
 175 
 176 static int essiv_skcipher_encrypt(struct skcipher_request *req)
 177 {
 178         return essiv_skcipher_crypt(req, true);
 179 }
 180 
 181 static int essiv_skcipher_decrypt(struct skcipher_request *req)
 182 {
 183         return essiv_skcipher_crypt(req, false);
 184 }
 185 
 186 static void essiv_aead_done(struct crypto_async_request *areq, int err)
 187 {
 188         struct aead_request *req = areq->data;
 189         struct essiv_aead_request_ctx *rctx = aead_request_ctx(req);
 190 
 191         if (rctx->assoc)
 192                 kfree(rctx->assoc);
 193         aead_request_complete(req, err);
 194 }
 195 
 196 static int essiv_aead_crypt(struct aead_request *req, bool enc)
 197 {
 198         struct crypto_aead *tfm = crypto_aead_reqtfm(req);
 199         const struct essiv_tfm_ctx *tctx = crypto_aead_ctx(tfm);
 200         struct essiv_aead_request_ctx *rctx = aead_request_ctx(req);
 201         struct aead_request *subreq = &rctx->aead_req;
 202         struct scatterlist *src = req->src;
 203         int err;
 204 
 205         crypto_cipher_encrypt_one(tctx->essiv_cipher, req->iv, req->iv);
 206 
 207         /*
 208          * dm-crypt embeds the sector number and the IV in the AAD region, so
 209          * we have to copy the converted IV into the right scatterlist before
 210          * we pass it on.
 211          */
 212         rctx->assoc = NULL;
 213         if (req->src == req->dst || !enc) {
 214                 scatterwalk_map_and_copy(req->iv, req->dst,
 215                                          req->assoclen - crypto_aead_ivsize(tfm),
 216                                          crypto_aead_ivsize(tfm), 1);
 217         } else {
 218                 u8 *iv = (u8 *)aead_request_ctx(req) + tctx->ivoffset;
 219                 int ivsize = crypto_aead_ivsize(tfm);
 220                 int ssize = req->assoclen - ivsize;
 221                 struct scatterlist *sg;
 222                 int nents;
 223 
 224                 if (ssize < 0)
 225                         return -EINVAL;
 226 
 227                 nents = sg_nents_for_len(req->src, ssize);
 228                 if (nents < 0)
 229                         return -EINVAL;
 230 
 231                 memcpy(iv, req->iv, ivsize);
 232                 sg_init_table(rctx->sg, 4);
 233 
 234                 if (unlikely(nents > 1)) {
 235                         /*
 236                          * This is a case that rarely occurs in practice, but
 237                          * for correctness, we have to deal with it nonetheless.
 238                          */
 239                         rctx->assoc = kmalloc(ssize, GFP_ATOMIC);
 240                         if (!rctx->assoc)
 241                                 return -ENOMEM;
 242 
 243                         scatterwalk_map_and_copy(rctx->assoc, req->src, 0,
 244                                                  ssize, 0);
 245                         sg_set_buf(rctx->sg, rctx->assoc, ssize);
 246                 } else {
 247                         sg_set_page(rctx->sg, sg_page(req->src), ssize,
 248                                     req->src->offset);
 249                 }
 250 
 251                 sg_set_buf(rctx->sg + 1, iv, ivsize);
 252                 sg = scatterwalk_ffwd(rctx->sg + 2, req->src, req->assoclen);
 253                 if (sg != rctx->sg + 2)
 254                         sg_chain(rctx->sg, 3, sg);
 255 
 256                 src = rctx->sg;
 257         }
 258 
 259         aead_request_set_tfm(subreq, tctx->u.aead);
 260         aead_request_set_ad(subreq, req->assoclen);
 261         aead_request_set_callback(subreq, aead_request_flags(req),
 262                                   essiv_aead_done, req);
 263         aead_request_set_crypt(subreq, src, req->dst, req->cryptlen, req->iv);
 264 
 265         err = enc ? crypto_aead_encrypt(subreq) :
 266                     crypto_aead_decrypt(subreq);
 267 
 268         if (rctx->assoc && err != -EINPROGRESS)
 269                 kfree(rctx->assoc);
 270         return err;
 271 }
 272 
 273 static int essiv_aead_encrypt(struct aead_request *req)
 274 {
 275         return essiv_aead_crypt(req, true);
 276 }
 277 
 278 static int essiv_aead_decrypt(struct aead_request *req)
 279 {
 280         return essiv_aead_crypt(req, false);
 281 }
 282 
 283 static int essiv_init_tfm(struct essiv_instance_ctx *ictx,
 284                           struct essiv_tfm_ctx *tctx)
 285 {
 286         struct crypto_cipher *essiv_cipher;
 287         struct crypto_shash *hash;
 288         int err;
 289 
 290         essiv_cipher = crypto_alloc_cipher(ictx->essiv_cipher_name, 0, 0);
 291         if (IS_ERR(essiv_cipher))
 292                 return PTR_ERR(essiv_cipher);
 293 
 294         hash = crypto_alloc_shash(ictx->shash_driver_name, 0, 0);
 295         if (IS_ERR(hash)) {
 296                 err = PTR_ERR(hash);
 297                 goto err_free_essiv_cipher;
 298         }
 299 
 300         tctx->essiv_cipher = essiv_cipher;
 301         tctx->hash = hash;
 302 
 303         return 0;
 304 
 305 err_free_essiv_cipher:
 306         crypto_free_cipher(essiv_cipher);
 307         return err;
 308 }
 309 
 310 static int essiv_skcipher_init_tfm(struct crypto_skcipher *tfm)
 311 {
 312         struct skcipher_instance *inst = skcipher_alg_instance(tfm);
 313         struct essiv_instance_ctx *ictx = skcipher_instance_ctx(inst);
 314         struct essiv_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
 315         struct crypto_skcipher *skcipher;
 316         int err;
 317 
 318         skcipher = crypto_spawn_skcipher(&ictx->u.skcipher_spawn);
 319         if (IS_ERR(skcipher))
 320                 return PTR_ERR(skcipher);
 321 
 322         crypto_skcipher_set_reqsize(tfm, sizeof(struct skcipher_request) +
 323                                          crypto_skcipher_reqsize(skcipher));
 324 
 325         err = essiv_init_tfm(ictx, tctx);
 326         if (err) {
 327                 crypto_free_skcipher(skcipher);
 328                 return err;
 329         }
 330 
 331         tctx->u.skcipher = skcipher;
 332         return 0;
 333 }
 334 
 335 static int essiv_aead_init_tfm(struct crypto_aead *tfm)
 336 {
 337         struct aead_instance *inst = aead_alg_instance(tfm);
 338         struct essiv_instance_ctx *ictx = aead_instance_ctx(inst);
 339         struct essiv_tfm_ctx *tctx = crypto_aead_ctx(tfm);
 340         struct crypto_aead *aead;
 341         unsigned int subreq_size;
 342         int err;
 343 
 344         BUILD_BUG_ON(offsetofend(struct essiv_aead_request_ctx, aead_req) !=
 345                      sizeof(struct essiv_aead_request_ctx));
 346 
 347         aead = crypto_spawn_aead(&ictx->u.aead_spawn);
 348         if (IS_ERR(aead))
 349                 return PTR_ERR(aead);
 350 
 351         subreq_size = FIELD_SIZEOF(struct essiv_aead_request_ctx, aead_req) +
 352                       crypto_aead_reqsize(aead);
 353 
 354         tctx->ivoffset = offsetof(struct essiv_aead_request_ctx, aead_req) +
 355                          subreq_size;
 356         crypto_aead_set_reqsize(tfm, tctx->ivoffset + crypto_aead_ivsize(aead));
 357 
 358         err = essiv_init_tfm(ictx, tctx);
 359         if (err) {
 360                 crypto_free_aead(aead);
 361                 return err;
 362         }
 363 
 364         tctx->u.aead = aead;
 365         return 0;
 366 }
 367 
 368 static void essiv_skcipher_exit_tfm(struct crypto_skcipher *tfm)
 369 {
 370         struct essiv_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
 371 
 372         crypto_free_skcipher(tctx->u.skcipher);
 373         crypto_free_cipher(tctx->essiv_cipher);
 374         crypto_free_shash(tctx->hash);
 375 }
 376 
 377 static void essiv_aead_exit_tfm(struct crypto_aead *tfm)
 378 {
 379         struct essiv_tfm_ctx *tctx = crypto_aead_ctx(tfm);
 380 
 381         crypto_free_aead(tctx->u.aead);
 382         crypto_free_cipher(tctx->essiv_cipher);
 383         crypto_free_shash(tctx->hash);
 384 }
 385 
 386 static void essiv_skcipher_free_instance(struct skcipher_instance *inst)
 387 {
 388         struct essiv_instance_ctx *ictx = skcipher_instance_ctx(inst);
 389 
 390         crypto_drop_skcipher(&ictx->u.skcipher_spawn);
 391         kfree(inst);
 392 }
 393 
 394 static void essiv_aead_free_instance(struct aead_instance *inst)
 395 {
 396         struct essiv_instance_ctx *ictx = aead_instance_ctx(inst);
 397 
 398         crypto_drop_aead(&ictx->u.aead_spawn);
 399         kfree(inst);
 400 }
 401 
 402 static bool parse_cipher_name(char *essiv_cipher_name, const char *cra_name)
 403 {
 404         const char *p, *q;
 405         int len;
 406 
 407         /* find the last opening parens */
 408         p = strrchr(cra_name, '(');
 409         if (!p++)
 410                 return false;
 411 
 412         /* find the first closing parens in the tail of the string */
 413         q = strchr(p, ')');
 414         if (!q)
 415                 return false;
 416 
 417         len = q - p;
 418         if (len >= CRYPTO_MAX_ALG_NAME)
 419                 return false;
 420 
 421         memcpy(essiv_cipher_name, p, len);
 422         essiv_cipher_name[len] = '\0';
 423         return true;
 424 }
 425 
 426 static bool essiv_supported_algorithms(const char *essiv_cipher_name,
 427                                        struct shash_alg *hash_alg,
 428                                        int ivsize)
 429 {
 430         struct crypto_alg *alg;
 431         bool ret = false;
 432 
 433         alg = crypto_alg_mod_lookup(essiv_cipher_name,
 434                                     CRYPTO_ALG_TYPE_CIPHER,
 435                                     CRYPTO_ALG_TYPE_MASK);
 436         if (IS_ERR(alg))
 437                 return false;
 438 
 439         if (hash_alg->digestsize < alg->cra_cipher.cia_min_keysize ||
 440             hash_alg->digestsize > alg->cra_cipher.cia_max_keysize)
 441                 goto out;
 442 
 443         if (ivsize != alg->cra_blocksize)
 444                 goto out;
 445 
 446         if (crypto_shash_alg_has_setkey(hash_alg))
 447                 goto out;
 448 
 449         ret = true;
 450 
 451 out:
 452         crypto_mod_put(alg);
 453         return ret;
 454 }
 455 
 456 static int essiv_create(struct crypto_template *tmpl, struct rtattr **tb)
 457 {
 458         struct crypto_attr_type *algt;
 459         const char *inner_cipher_name;
 460         const char *shash_name;
 461         struct skcipher_instance *skcipher_inst = NULL;
 462         struct aead_instance *aead_inst = NULL;
 463         struct crypto_instance *inst;
 464         struct crypto_alg *base, *block_base;
 465         struct essiv_instance_ctx *ictx;
 466         struct skcipher_alg *skcipher_alg = NULL;
 467         struct aead_alg *aead_alg = NULL;
 468         struct crypto_alg *_hash_alg;
 469         struct shash_alg *hash_alg;
 470         int ivsize;
 471         u32 type;
 472         int err;
 473 
 474         algt = crypto_get_attr_type(tb);
 475         if (IS_ERR(algt))
 476                 return PTR_ERR(algt);
 477 
 478         inner_cipher_name = crypto_attr_alg_name(tb[1]);
 479         if (IS_ERR(inner_cipher_name))
 480                 return PTR_ERR(inner_cipher_name);
 481 
 482         shash_name = crypto_attr_alg_name(tb[2]);
 483         if (IS_ERR(shash_name))
 484                 return PTR_ERR(shash_name);
 485 
 486         type = algt->type & algt->mask;
 487 
 488         switch (type) {
 489         case CRYPTO_ALG_TYPE_BLKCIPHER:
 490                 skcipher_inst = kzalloc(sizeof(*skcipher_inst) +
 491                                         sizeof(*ictx), GFP_KERNEL);
 492                 if (!skcipher_inst)
 493                         return -ENOMEM;
 494                 inst = skcipher_crypto_instance(skcipher_inst);
 495                 base = &skcipher_inst->alg.base;
 496                 ictx = crypto_instance_ctx(inst);
 497 
 498                 /* Symmetric cipher, e.g., "cbc(aes)" */
 499                 crypto_set_skcipher_spawn(&ictx->u.skcipher_spawn, inst);
 500                 err = crypto_grab_skcipher(&ictx->u.skcipher_spawn,
 501                                            inner_cipher_name, 0,
 502                                            crypto_requires_sync(algt->type,
 503                                                                 algt->mask));
 504                 if (err)
 505                         goto out_free_inst;
 506                 skcipher_alg = crypto_spawn_skcipher_alg(&ictx->u.skcipher_spawn);
 507                 block_base = &skcipher_alg->base;
 508                 ivsize = crypto_skcipher_alg_ivsize(skcipher_alg);
 509                 break;
 510 
 511         case CRYPTO_ALG_TYPE_AEAD:
 512                 aead_inst = kzalloc(sizeof(*aead_inst) +
 513                                     sizeof(*ictx), GFP_KERNEL);
 514                 if (!aead_inst)
 515                         return -ENOMEM;
 516                 inst = aead_crypto_instance(aead_inst);
 517                 base = &aead_inst->alg.base;
 518                 ictx = crypto_instance_ctx(inst);
 519 
 520                 /* AEAD cipher, e.g., "authenc(hmac(sha256),cbc(aes))" */
 521                 crypto_set_aead_spawn(&ictx->u.aead_spawn, inst);
 522                 err = crypto_grab_aead(&ictx->u.aead_spawn,
 523                                        inner_cipher_name, 0,
 524                                        crypto_requires_sync(algt->type,
 525                                                             algt->mask));
 526                 if (err)
 527                         goto out_free_inst;
 528                 aead_alg = crypto_spawn_aead_alg(&ictx->u.aead_spawn);
 529                 block_base = &aead_alg->base;
 530                 if (!strstarts(block_base->cra_name, "authenc(")) {
 531                         pr_warn("Only authenc() type AEADs are supported by ESSIV\n");
 532                         err = -EINVAL;
 533                         goto out_drop_skcipher;
 534                 }
 535                 ivsize = aead_alg->ivsize;
 536                 break;
 537 
 538         default:
 539                 return -EINVAL;
 540         }
 541 
 542         if (!parse_cipher_name(ictx->essiv_cipher_name, block_base->cra_name)) {
 543                 pr_warn("Failed to parse ESSIV cipher name from skcipher cra_name\n");
 544                 err = -EINVAL;
 545                 goto out_drop_skcipher;
 546         }
 547 
 548         /* Synchronous hash, e.g., "sha256" */
 549         _hash_alg = crypto_alg_mod_lookup(shash_name,
 550                                           CRYPTO_ALG_TYPE_SHASH,
 551                                           CRYPTO_ALG_TYPE_MASK);
 552         if (IS_ERR(_hash_alg)) {
 553                 err = PTR_ERR(_hash_alg);
 554                 goto out_drop_skcipher;
 555         }
 556         hash_alg = __crypto_shash_alg(_hash_alg);
 557 
 558         /* Check the set of algorithms */
 559         if (!essiv_supported_algorithms(ictx->essiv_cipher_name, hash_alg,
 560                                         ivsize)) {
 561                 pr_warn("Unsupported essiv instantiation: essiv(%s,%s)\n",
 562                         block_base->cra_name, hash_alg->base.cra_name);
 563                 err = -EINVAL;
 564                 goto out_free_hash;
 565         }
 566 
 567         /* record the driver name so we can instantiate this exact algo later */
 568         strlcpy(ictx->shash_driver_name, hash_alg->base.cra_driver_name,
 569                 CRYPTO_MAX_ALG_NAME);
 570 
 571         /* Instance fields */
 572 
 573         err = -ENAMETOOLONG;
 574         if (snprintf(base->cra_name, CRYPTO_MAX_ALG_NAME,
 575                      "essiv(%s,%s)", block_base->cra_name,
 576                      hash_alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
 577                 goto out_free_hash;
 578         if (snprintf(base->cra_driver_name, CRYPTO_MAX_ALG_NAME,
 579                      "essiv(%s,%s)", block_base->cra_driver_name,
 580                      hash_alg->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 581                 goto out_free_hash;
 582 
 583         base->cra_flags         = block_base->cra_flags & CRYPTO_ALG_ASYNC;
 584         base->cra_blocksize     = block_base->cra_blocksize;
 585         base->cra_ctxsize       = sizeof(struct essiv_tfm_ctx);
 586         base->cra_alignmask     = block_base->cra_alignmask;
 587         base->cra_priority      = block_base->cra_priority;
 588 
 589         if (type == CRYPTO_ALG_TYPE_BLKCIPHER) {
 590                 skcipher_inst->alg.setkey       = essiv_skcipher_setkey;
 591                 skcipher_inst->alg.encrypt      = essiv_skcipher_encrypt;
 592                 skcipher_inst->alg.decrypt      = essiv_skcipher_decrypt;
 593                 skcipher_inst->alg.init         = essiv_skcipher_init_tfm;
 594                 skcipher_inst->alg.exit         = essiv_skcipher_exit_tfm;
 595 
 596                 skcipher_inst->alg.min_keysize  = crypto_skcipher_alg_min_keysize(skcipher_alg);
 597                 skcipher_inst->alg.max_keysize  = crypto_skcipher_alg_max_keysize(skcipher_alg);
 598                 skcipher_inst->alg.ivsize       = ivsize;
 599                 skcipher_inst->alg.chunksize    = crypto_skcipher_alg_chunksize(skcipher_alg);
 600                 skcipher_inst->alg.walksize     = crypto_skcipher_alg_walksize(skcipher_alg);
 601 
 602                 skcipher_inst->free             = essiv_skcipher_free_instance;
 603 
 604                 err = skcipher_register_instance(tmpl, skcipher_inst);
 605         } else {
 606                 aead_inst->alg.setkey           = essiv_aead_setkey;
 607                 aead_inst->alg.setauthsize      = essiv_aead_setauthsize;
 608                 aead_inst->alg.encrypt          = essiv_aead_encrypt;
 609                 aead_inst->alg.decrypt          = essiv_aead_decrypt;
 610                 aead_inst->alg.init             = essiv_aead_init_tfm;
 611                 aead_inst->alg.exit             = essiv_aead_exit_tfm;
 612 
 613                 aead_inst->alg.ivsize           = ivsize;
 614                 aead_inst->alg.maxauthsize      = crypto_aead_alg_maxauthsize(aead_alg);
 615                 aead_inst->alg.chunksize        = crypto_aead_alg_chunksize(aead_alg);
 616 
 617                 aead_inst->free                 = essiv_aead_free_instance;
 618 
 619                 err = aead_register_instance(tmpl, aead_inst);
 620         }
 621 
 622         if (err)
 623                 goto out_free_hash;
 624 
 625         crypto_mod_put(_hash_alg);
 626         return 0;
 627 
 628 out_free_hash:
 629         crypto_mod_put(_hash_alg);
 630 out_drop_skcipher:
 631         if (type == CRYPTO_ALG_TYPE_BLKCIPHER)
 632                 crypto_drop_skcipher(&ictx->u.skcipher_spawn);
 633         else
 634                 crypto_drop_aead(&ictx->u.aead_spawn);
 635 out_free_inst:
 636         kfree(skcipher_inst);
 637         kfree(aead_inst);
 638         return err;
 639 }
 640 
 641 /* essiv(cipher_name, shash_name) */
 642 static struct crypto_template essiv_tmpl = {
 643         .name   = "essiv",
 644         .create = essiv_create,
 645         .module = THIS_MODULE,
 646 };
 647 
 648 static int __init essiv_module_init(void)
 649 {
 650         return crypto_register_template(&essiv_tmpl);
 651 }
 652 
 653 static void __exit essiv_module_exit(void)
 654 {
 655         crypto_unregister_template(&essiv_tmpl);
 656 }
 657 
 658 subsys_initcall(essiv_module_init);
 659 module_exit(essiv_module_exit);
 660 
 661 MODULE_DESCRIPTION("ESSIV skcipher/aead wrapper for block encryption");
 662 MODULE_LICENSE("GPL v2");
 663 MODULE_ALIAS_CRYPTO("essiv");