crypto/authenc.c

   1 /*
   2  * Authenc: Simple AEAD wrapper for IPsec
   3  *
   4  * Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au>
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the Free
   8  * Software Foundation; either version 2 of the License, or (at your option)
   9  * any later version.
  10  *
  11  */
  12
  13 #include <crypto/internal/aead.h>
  14 #include <crypto/internal/hash.h>
  15 #include <crypto/internal/skcipher.h>
  16 #include <crypto/authenc.h>
  17 #include <crypto/null.h>
  18 #include <crypto/scatterwalk.h>
  19 #include <linux/err.h>
  20 #include <linux/init.h>
  21 #include <linux/kernel.h>
  22 #include <linux/module.h>
  23 #include <linux/rtnetlink.h>
  24 #include <linux/slab.h>
  25 #include <linux/spinlock.h>
  26
  27 struct authenc_instance_ctx {
  28         struct crypto_ahash_spawn auth;
  29         struct crypto_skcipher_spawn enc;
  30         unsigned int reqoff;
  31 };
  32
  33 struct crypto_authenc_ctx {
  34         struct crypto_ahash *auth;
  35         struct crypto_skcipher *enc;
  36         struct crypto_skcipher *null;
  37 };
  38
  39 struct authenc_request_ctx {
  40         struct scatterlist src[2];
  41         struct scatterlist dst[2];
  42         char tail[];
  43 };
  44
  45 static void authenc_request_complete(struct aead_request *req, int err)
  46 {
  47         if (err != -EINPROGRESS)
  48                 aead_request_complete(req, err);
  49 }
  50
  51 int crypto_authenc_extractkeys(struct crypto_authenc_keys *keys, const u8 *key,
  52                                unsigned int keylen)
  53 {
  54         struct rtattr *rta = (struct rtattr *)key;
  55         struct crypto_authenc_key_param *param;
  56
  57         if (!RTA_OK(rta, keylen))
  58                 return -EINVAL;
  59         if (rta->rta_type != CRYPTO_AUTHENC_KEYA_PARAM)
  60                 return -EINVAL;
  61         if (RTA_PAYLOAD(rta) < sizeof(*param))
  62                 return -EINVAL;
  63
  64         param = RTA_DATA(rta);
  65         keys->enckeylen = be32_to_cpu(param->enckeylen);
  66
  67         key += RTA_ALIGN(rta->rta_len);
  68         keylen -= RTA_ALIGN(rta->rta_len);
  69
  70         if (keylen < keys->enckeylen)
  71                 return -EINVAL;
  72
  73         keys->authkeylen = keylen - keys->enckeylen;
  74         keys->authkey = key;
  75         keys->enckey = key + keys->authkeylen;
  76
  77         return 0;
  78 }
  79 EXPORT_SYMBOL_GPL(crypto_authenc_extractkeys);
  80
  81 static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
  82                                  unsigned int keylen)
  83 {
  84         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  85         struct crypto_ahash *auth = ctx->auth;
  86         struct crypto_skcipher *enc = ctx->enc;
  87         struct crypto_authenc_keys keys;
  88         int err = -EINVAL;
  89
  90         if (crypto_authenc_extractkeys(&keys, key, keylen) != 0)
  91                 goto badkey;
  92
  93         crypto_ahash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
  94         crypto_ahash_set_flags(auth, crypto_aead_get_flags(authenc) &
  95                                     CRYPTO_TFM_REQ_MASK);
  96         err = crypto_ahash_setkey(auth, keys.authkey, keys.authkeylen);
  97         crypto_aead_set_flags(authenc, crypto_ahash_get_flags(auth) &
  98                                        CRYPTO_TFM_RES_MASK);
  99
 100         if (err)
 101                 goto out;
 102
 103         crypto_skcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
 104         crypto_skcipher_set_flags(enc, crypto_aead_get_flags(authenc) &
 105                                        CRYPTO_TFM_REQ_MASK);
 106         err = crypto_skcipher_setkey(enc, keys.enckey, keys.enckeylen);
 107         crypto_aead_set_flags(authenc, crypto_skcipher_get_flags(enc) &
 108                                        CRYPTO_TFM_RES_MASK);
 109
 110 out:
 111         return err;
 112
 113 badkey:
 114         crypto_aead_set_flags(authenc, CRYPTO_TFM_RES_BAD_KEY_LEN);
 115         goto out;
 116 }
 117
 118 static void authenc_geniv_ahash_done(struct crypto_async_request *areq, int err)
 119 {
 120         struct aead_request *req = areq->data;
 121         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 122         struct aead_instance *inst = aead_alg_instance(authenc);
 123         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 124         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 125         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 126
 127         if (err)
 128                 goto out;
 129
 130         scatterwalk_map_and_copy(ahreq->result, req->dst,
 131                                  req->assoclen + req->cryptlen,
 132                                  crypto_aead_authsize(authenc), 1);
 133
 134 out:
 135         aead_request_complete(req, err);
 136 }
 137
 138 static int crypto_authenc_genicv(struct aead_request *req, unsigned int flags)
 139 {
 140         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 141         struct aead_instance *inst = aead_alg_instance(authenc);
 142         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 143         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 144         struct crypto_ahash *auth = ctx->auth;
 145         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 146         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 147         u8 *hash = areq_ctx->tail;
 148         int err;
 149
 150         hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
 151                            crypto_ahash_alignmask(auth) + 1);
 152
 153         ahash_request_set_tfm(ahreq, auth);
 154         ahash_request_set_crypt(ahreq, req->dst, hash,
 155                                 req->assoclen + req->cryptlen);
 156         ahash_request_set_callback(ahreq, flags,
 157                                    authenc_geniv_ahash_done, req);
 158
 159         err = crypto_ahash_digest(ahreq);
 160         if (err)
 161                 return err;
 162
 163         scatterwalk_map_and_copy(hash, req->dst, req->assoclen + req->cryptlen,
 164                                  crypto_aead_authsize(authenc), 1);
 165
 166         return 0;
 167 }
 168
 169 static void crypto_authenc_encrypt_done(struct crypto_async_request *req,
 170                                         int err)
 171 {
 172         struct aead_request *areq = req->data;
 173
 174         if (err)
 175                 goto out;
 176
 177         err = crypto_authenc_genicv(areq, 0);
 178
 179 out:
 180         authenc_request_complete(areq, err);
 181 }
 182
 183 static int crypto_authenc_copy_assoc(struct aead_request *req)
 184 {
 185         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 186         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 187         SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);
 188
 189         skcipher_request_set_tfm(skreq, ctx->null);
 190         skcipher_request_set_callback(skreq, aead_request_flags(req),
 191                                       NULL, NULL);
 192         skcipher_request_set_crypt(skreq, req->src, req->dst, req->assoclen,
 193                                    NULL);
 194
 195         return crypto_skcipher_encrypt(skreq);
 196 }
 197
 198 static int crypto_authenc_encrypt(struct aead_request *req)
 199 {
 200         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 201         struct aead_instance *inst = aead_alg_instance(authenc);
 202         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 203         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 204         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 205         struct crypto_skcipher *enc = ctx->enc;
 206         unsigned int cryptlen = req->cryptlen;
 207         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 208                                                   ictx->reqoff);
 209         struct scatterlist *src, *dst;
 210         int err;
 211
 212         src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
 213         dst = src;
 214
 215         if (req->src != req->dst) {
 216                 err = crypto_authenc_copy_assoc(req);
 217                 if (err)
 218                         return err;
 219
 220                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
 221         }
 222
 223         skcipher_request_set_tfm(skreq, enc);
 224         skcipher_request_set_callback(skreq, aead_request_flags(req),
 225                                       crypto_authenc_encrypt_done, req);
 226         skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
 227
 228         err = crypto_skcipher_encrypt(skreq);
 229         if (err)
 230                 return err;
 231
 232         return crypto_authenc_genicv(req, aead_request_flags(req));
 233 }
 234
 235 static int crypto_authenc_decrypt_tail(struct aead_request *req,
 236                                        unsigned int flags)
 237 {
 238         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 239         struct aead_instance *inst = aead_alg_instance(authenc);
 240         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 241         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 242         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 243         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 244         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 245                                                   ictx->reqoff);
 246         unsigned int authsize = crypto_aead_authsize(authenc);
 247         u8 *ihash = ahreq->result + authsize;
 248         struct scatterlist *src, *dst;
 249
 250         scatterwalk_map_and_copy(ihash, req->src, ahreq->nbytes, authsize, 0);
 251
 252         if (crypto_memneq(ihash, ahreq->result, authsize))
 253                 return -EBADMSG;
 254
 255         src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
 256         dst = src;
 257
 258         if (req->src != req->dst)
 259                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
 260
 261         skcipher_request_set_tfm(skreq, ctx->enc);
 262         skcipher_request_set_callback(skreq, aead_request_flags(req),
 263                                       req->base.complete, req->base.data);
 264         skcipher_request_set_crypt(skreq, src, dst,
 265                                    req->cryptlen - authsize, req->iv);
 266
 267         return crypto_skcipher_decrypt(skreq);
 268 }
 269
 270 static void authenc_verify_ahash_done(struct crypto_async_request *areq,
 271                                       int err)
 272 {
 273         struct aead_request *req = areq->data;
 274
 275         if (err)
 276                 goto out;
 277
 278         err = crypto_authenc_decrypt_tail(req, 0);
 279
 280 out:
 281         authenc_request_complete(req, err);
 282 }
 283
 284 static int crypto_authenc_decrypt(struct aead_request *req)
 285 {
 286         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 287         unsigned int authsize = crypto_aead_authsize(authenc);
 288         struct aead_instance *inst = aead_alg_instance(authenc);
 289         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 290         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 291         struct crypto_ahash *auth = ctx->auth;
 292         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 293         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 294         u8 *hash = areq_ctx->tail;
 295         int err;
 296
 297         hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
 298                            crypto_ahash_alignmask(auth) + 1);
 299
 300         ahash_request_set_tfm(ahreq, auth);
 301         ahash_request_set_crypt(ahreq, req->src, hash,
 302                                 req->assoclen + req->cryptlen - authsize);
 303         ahash_request_set_callback(ahreq, aead_request_flags(req),
 304                                    authenc_verify_ahash_done, req);
 305
 306         err = crypto_ahash_digest(ahreq);
 307         if (err)
 308                 return err;
 309
 310         return crypto_authenc_decrypt_tail(req, aead_request_flags(req));
 311 }
 312
 313 static int crypto_authenc_init_tfm(struct crypto_aead *tfm)
 314 {
 315         struct aead_instance *inst = aead_alg_instance(tfm);
 316         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 317         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
 318         struct crypto_ahash *auth;
 319         struct crypto_skcipher *enc;
 320         struct crypto_skcipher *null;
 321         int err;
 322
 323         auth = crypto_spawn_ahash(&ictx->auth);
 324         if (IS_ERR(auth))
 325                 return PTR_ERR(auth);
 326
 327         enc = crypto_spawn_skcipher(&ictx->enc);
 328         err = PTR_ERR(enc);
 329         if (IS_ERR(enc))
 330                 goto err_free_ahash;
 331
 332         null = crypto_get_default_null_skcipher();
 333         err = PTR_ERR(null);
 334         if (IS_ERR(null))
 335                 goto err_free_skcipher;
 336
 337         ctx->auth = auth;
 338         ctx->enc = enc;
 339         ctx->null = null;
 340
 341         crypto_aead_set_reqsize(
 342                 tfm,
 343                 sizeof(struct authenc_request_ctx) +
 344                 ictx->reqoff +
 345                 max_t(unsigned int,
 346                       crypto_ahash_reqsize(auth) +
 347                       sizeof(struct ahash_request),
 348                       sizeof(struct skcipher_request) +
 349                       crypto_skcipher_reqsize(enc)));
 350
 351         return 0;
 352
 353 err_free_skcipher:
 354         crypto_free_skcipher(enc);
 355 err_free_ahash:
 356         crypto_free_ahash(auth);
 357         return err;
 358 }
 359
 360 static void crypto_authenc_exit_tfm(struct crypto_aead *tfm)
 361 {
 362         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
 363
 364         crypto_free_ahash(ctx->auth);
 365         crypto_free_skcipher(ctx->enc);
 366         crypto_put_default_null_skcipher();
 367 }
 368
 369 static void crypto_authenc_free(struct aead_instance *inst)
 370 {
 371         struct authenc_instance_ctx *ctx = aead_instance_ctx(inst);
 372
 373         crypto_drop_skcipher(&ctx->enc);
 374         crypto_drop_ahash(&ctx->auth);
 375         kfree(inst);
 376 }
 377
 378 static int crypto_authenc_create(struct crypto_template *tmpl,
 379                                  struct rtattr **tb)
 380 {
 381         struct crypto_attr_type *algt;
 382         struct aead_instance *inst;
 383         struct hash_alg_common *auth;
 384         struct crypto_alg *auth_base;
 385         struct skcipher_alg *enc;
 386         struct authenc_instance_ctx *ctx;
 387         const char *enc_name;
 388         int err;
 389
 390         algt = crypto_get_attr_type(tb);
 391         if (IS_ERR(algt))
 392                 return PTR_ERR(algt);
 393
 394         if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
 395                 return -EINVAL;
 396
 397         auth = ahash_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
 398                               CRYPTO_ALG_TYPE_AHASH_MASK |
 399                               crypto_requires_sync(algt->type, algt->mask));
 400         if (IS_ERR(auth))
 401                 return PTR_ERR(auth);
 402
 403         auth_base = &auth->base;
 404
 405         enc_name = crypto_attr_alg_name(tb[2]);
 406         err = PTR_ERR(enc_name);
 407         if (IS_ERR(enc_name))
 408                 goto out_put_auth;
 409
 410         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 411         err = -ENOMEM;
 412         if (!inst)
 413                 goto out_put_auth;
 414
 415         ctx = aead_instance_ctx(inst);
 416
 417         err = crypto_init_ahash_spawn(&ctx->auth, auth,
 418                                       aead_crypto_instance(inst));
 419         if (err)
 420                 goto err_free_inst;
 421
 422         crypto_set_skcipher_spawn(&ctx->enc, aead_crypto_instance(inst));
 423         err = crypto_grab_skcipher(&ctx->enc, enc_name, 0,
 424                                    crypto_requires_sync(algt->type,
 425                                                         algt->mask));
 426         if (err)
 427                 goto err_drop_auth;
 428
 429         enc = crypto_spawn_skcipher_alg(&ctx->enc);
 430
 431         ctx->reqoff = ALIGN(2 * auth->digestsize + auth_base->cra_alignmask,
 432                             auth_base->cra_alignmask + 1);
 433
 434         err = -ENAMETOOLONG;
 435         if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 436                      "authenc(%s,%s)", auth_base->cra_name,
 437                      enc->base.cra_name) >=
 438             CRYPTO_MAX_ALG_NAME)
 439                 goto err_drop_enc;
 440
 441         if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 442                      "authenc(%s,%s)", auth_base->cra_driver_name,
 443                      enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 444                 goto err_drop_enc;
 445
 446         inst->alg.base.cra_flags = (auth_base->cra_flags |
 447                                     enc->base.cra_flags) & CRYPTO_ALG_ASYNC;
 448         inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
 449                                       auth_base->cra_priority;
 450         inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
 451         inst->alg.base.cra_alignmask = auth_base->cra_alignmask |
 452                                        enc->base.cra_alignmask;
 453         inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
 454
 455         inst->alg.ivsize = crypto_skcipher_alg_ivsize(enc);
 456         inst->alg.chunksize = crypto_skcipher_alg_chunksize(enc);
 457         inst->alg.maxauthsize = auth->digestsize;
 458
 459         inst->alg.init = crypto_authenc_init_tfm;
 460         inst->alg.exit = crypto_authenc_exit_tfm;
 461
 462         inst->alg.setkey = crypto_authenc_setkey;
 463         inst->alg.encrypt = crypto_authenc_encrypt;
 464         inst->alg.decrypt = crypto_authenc_decrypt;
 465
 466         inst->free = crypto_authenc_free;
 467
 468         err = aead_register_instance(tmpl, inst);
 469         if (err)
 470                 goto err_drop_enc;
 471
 472 out:
 473         crypto_mod_put(auth_base);
 474         return err;
 475
 476 err_drop_enc:
 477         crypto_drop_skcipher(&ctx->enc);
 478 err_drop_auth:
 479         crypto_drop_ahash(&ctx->auth);
 480 err_free_inst:
 481         kfree(inst);
 482 out_put_auth:
 483         goto out;
 484 }
 485
 486 static struct crypto_template crypto_authenc_tmpl = {
 487         .name = "authenc",
 488         .create = crypto_authenc_create,
 489         .module = THIS_MODULE,
 490 };
 491
 492 static int __init crypto_authenc_module_init(void)
 493 {
 494         return crypto_register_template(&crypto_authenc_tmpl);
 495 }
 496
 497 static void __exit crypto_authenc_module_exit(void)
 498 {
 499         crypto_unregister_template(&crypto_authenc_tmpl);
 500 }
 501
 502 module_init(crypto_authenc_module_init);
 503 module_exit(crypto_authenc_module_exit);
 504
 505 MODULE_LICENSE("GPL");
 506 MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");
 507 MODULE_ALIAS_CRYPTO("authenc");