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         memzero_explicit(&keys, sizeof(keys));
 112         return err;
 113
 114 badkey:
 115         crypto_aead_set_flags(authenc, CRYPTO_TFM_RES_BAD_KEY_LEN);
 116         goto out;
 117 }
 118
 119 static void authenc_geniv_ahash_done(struct crypto_async_request *areq, int err)
 120 {
 121         struct aead_request *req = areq->data;
 122         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 123         struct aead_instance *inst = aead_alg_instance(authenc);
 124         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 125         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 126         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 127
 128         if (err)
 129                 goto out;
 130
 131         scatterwalk_map_and_copy(ahreq->result, req->dst,
 132                                  req->assoclen + req->cryptlen,
 133                                  crypto_aead_authsize(authenc), 1);
 134
 135 out:
 136         aead_request_complete(req, err);
 137 }
 138
 139 static int crypto_authenc_genicv(struct aead_request *req, unsigned int flags)
 140 {
 141         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 142         struct aead_instance *inst = aead_alg_instance(authenc);
 143         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 144         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 145         struct crypto_ahash *auth = ctx->auth;
 146         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 147         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 148         u8 *hash = areq_ctx->tail;
 149         int err;
 150
 151         hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
 152                            crypto_ahash_alignmask(auth) + 1);
 153
 154         ahash_request_set_tfm(ahreq, auth);
 155         ahash_request_set_crypt(ahreq, req->dst, hash,
 156                                 req->assoclen + req->cryptlen);
 157         ahash_request_set_callback(ahreq, flags,
 158                                    authenc_geniv_ahash_done, req);
 159
 160         err = crypto_ahash_digest(ahreq);
 161         if (err)
 162                 return err;
 163
 164         scatterwalk_map_and_copy(hash, req->dst, req->assoclen + req->cryptlen,
 165                                  crypto_aead_authsize(authenc), 1);
 166
 167         return 0;
 168 }
 169
 170 static void crypto_authenc_encrypt_done(struct crypto_async_request *req,
 171                                         int err)
 172 {
 173         struct aead_request *areq = req->data;
 174
 175         if (err)
 176                 goto out;
 177
 178         err = crypto_authenc_genicv(areq, 0);
 179
 180 out:
 181         authenc_request_complete(areq, err);
 182 }
 183
 184 static int crypto_authenc_copy_assoc(struct aead_request *req)
 185 {
 186         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 187         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 188         SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);
 189
 190         skcipher_request_set_tfm(skreq, ctx->null);
 191         skcipher_request_set_callback(skreq, aead_request_flags(req),
 192                                       NULL, NULL);
 193         skcipher_request_set_crypt(skreq, req->src, req->dst, req->assoclen,
 194                                    NULL);
 195
 196         return crypto_skcipher_encrypt(skreq);
 197 }
 198
 199 static int crypto_authenc_encrypt(struct aead_request *req)
 200 {
 201         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 202         struct aead_instance *inst = aead_alg_instance(authenc);
 203         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 204         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 205         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 206         struct crypto_skcipher *enc = ctx->enc;
 207         unsigned int cryptlen = req->cryptlen;
 208         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 209                                                   ictx->reqoff);
 210         struct scatterlist *src, *dst;
 211         int err;
 212
 213         src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
 214         dst = src;
 215
 216         if (req->src != req->dst) {
 217                 err = crypto_authenc_copy_assoc(req);
 218                 if (err)
 219                         return err;
 220
 221                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
 222         }
 223
 224         skcipher_request_set_tfm(skreq, enc);
 225         skcipher_request_set_callback(skreq, aead_request_flags(req),
 226                                       crypto_authenc_encrypt_done, req);
 227         skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
 228
 229         err = crypto_skcipher_encrypt(skreq);
 230         if (err)
 231                 return err;
 232
 233         return crypto_authenc_genicv(req, aead_request_flags(req));
 234 }
 235
 236 static int crypto_authenc_decrypt_tail(struct aead_request *req,
 237                                        unsigned int flags)
 238 {
 239         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 240         struct aead_instance *inst = aead_alg_instance(authenc);
 241         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 242         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 243         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 244         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 245         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 246                                                   ictx->reqoff);
 247         unsigned int authsize = crypto_aead_authsize(authenc);
 248         u8 *ihash = ahreq->result + authsize;
 249         struct scatterlist *src, *dst;
 250
 251         scatterwalk_map_and_copy(ihash, req->src, ahreq->nbytes, authsize, 0);
 252
 253         if (crypto_memneq(ihash, ahreq->result, authsize))
 254                 return -EBADMSG;
 255
 256         src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
 257         dst = src;
 258
 259         if (req->src != req->dst)
 260                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
 261
 262         skcipher_request_set_tfm(skreq, ctx->enc);
 263         skcipher_request_set_callback(skreq, aead_request_flags(req),
 264                                       req->base.complete, req->base.data);
 265         skcipher_request_set_crypt(skreq, src, dst,
 266                                    req->cryptlen - authsize, req->iv);
 267
 268         return crypto_skcipher_decrypt(skreq);
 269 }
 270
 271 static void authenc_verify_ahash_done(struct crypto_async_request *areq,
 272                                       int err)
 273 {
 274         struct aead_request *req = areq->data;
 275
 276         if (err)
 277                 goto out;
 278
 279         err = crypto_authenc_decrypt_tail(req, 0);
 280
 281 out:
 282         authenc_request_complete(req, err);
 283 }
 284
 285 static int crypto_authenc_decrypt(struct aead_request *req)
 286 {
 287         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 288         unsigned int authsize = crypto_aead_authsize(authenc);
 289         struct aead_instance *inst = aead_alg_instance(authenc);
 290         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 291         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 292         struct crypto_ahash *auth = ctx->auth;
 293         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 294         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 295         u8 *hash = areq_ctx->tail;
 296         int err;
 297
 298         hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
 299                            crypto_ahash_alignmask(auth) + 1);
 300
 301         ahash_request_set_tfm(ahreq, auth);
 302         ahash_request_set_crypt(ahreq, req->src, hash,
 303                                 req->assoclen + req->cryptlen - authsize);
 304         ahash_request_set_callback(ahreq, aead_request_flags(req),
 305                                    authenc_verify_ahash_done, req);
 306
 307         err = crypto_ahash_digest(ahreq);
 308         if (err)
 309                 return err;
 310
 311         return crypto_authenc_decrypt_tail(req, aead_request_flags(req));
 312 }
 313
 314 static int crypto_authenc_init_tfm(struct crypto_aead *tfm)
 315 {
 316         struct aead_instance *inst = aead_alg_instance(tfm);
 317         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 318         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
 319         struct crypto_ahash *auth;
 320         struct crypto_skcipher *enc;
 321         struct crypto_skcipher *null;
 322         int err;
 323
 324         auth = crypto_spawn_ahash(&ictx->auth);
 325         if (IS_ERR(auth))
 326                 return PTR_ERR(auth);
 327
 328         enc = crypto_spawn_skcipher(&ictx->enc);
 329         err = PTR_ERR(enc);
 330         if (IS_ERR(enc))
 331                 goto err_free_ahash;
 332
 333         null = crypto_get_default_null_skcipher();
 334         err = PTR_ERR(null);
 335         if (IS_ERR(null))
 336                 goto err_free_skcipher;
 337
 338         ctx->auth = auth;
 339         ctx->enc = enc;
 340         ctx->null = null;
 341
 342         crypto_aead_set_reqsize(
 343                 tfm,
 344                 sizeof(struct authenc_request_ctx) +
 345                 ictx->reqoff +
 346                 max_t(unsigned int,
 347                       crypto_ahash_reqsize(auth) +
 348                       sizeof(struct ahash_request),
 349                       sizeof(struct skcipher_request) +
 350                       crypto_skcipher_reqsize(enc)));
 351
 352         return 0;
 353
 354 err_free_skcipher:
 355         crypto_free_skcipher(enc);
 356 err_free_ahash:
 357         crypto_free_ahash(auth);
 358         return err;
 359 }
 360
 361 static void crypto_authenc_exit_tfm(struct crypto_aead *tfm)
 362 {
 363         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
 364
 365         crypto_free_ahash(ctx->auth);
 366         crypto_free_skcipher(ctx->enc);
 367         crypto_put_default_null_skcipher();
 368 }
 369
 370 static void crypto_authenc_free(struct aead_instance *inst)
 371 {
 372         struct authenc_instance_ctx *ctx = aead_instance_ctx(inst);
 373
 374         crypto_drop_skcipher(&ctx->enc);
 375         crypto_drop_ahash(&ctx->auth);
 376         kfree(inst);
 377 }
 378
 379 static int crypto_authenc_create(struct crypto_template *tmpl,
 380                                  struct rtattr **tb)
 381 {
 382         struct crypto_attr_type *algt;
 383         struct aead_instance *inst;
 384         struct hash_alg_common *auth;
 385         struct crypto_alg *auth_base;
 386         struct skcipher_alg *enc;
 387         struct authenc_instance_ctx *ctx;
 388         const char *enc_name;
 389         int err;
 390
 391         algt = crypto_get_attr_type(tb);
 392         if (IS_ERR(algt))
 393                 return PTR_ERR(algt);
 394
 395         if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
 396                 return -EINVAL;
 397
 398         auth = ahash_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
 399                               CRYPTO_ALG_TYPE_AHASH_MASK |
 400                               crypto_requires_sync(algt->type, algt->mask));
 401         if (IS_ERR(auth))
 402                 return PTR_ERR(auth);
 403
 404         auth_base = &auth->base;
 405
 406         enc_name = crypto_attr_alg_name(tb[2]);
 407         err = PTR_ERR(enc_name);
 408         if (IS_ERR(enc_name))
 409                 goto out_put_auth;
 410
 411         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 412         err = -ENOMEM;
 413         if (!inst)
 414                 goto out_put_auth;
 415
 416         ctx = aead_instance_ctx(inst);
 417
 418         err = crypto_init_ahash_spawn(&ctx->auth, auth,
 419                                       aead_crypto_instance(inst));
 420         if (err)
 421                 goto err_free_inst;
 422
 423         crypto_set_skcipher_spawn(&ctx->enc, aead_crypto_instance(inst));
 424         err = crypto_grab_skcipher(&ctx->enc, enc_name, 0,
 425                                    crypto_requires_sync(algt->type,
 426                                                         algt->mask));
 427         if (err)
 428                 goto err_drop_auth;
 429
 430         enc = crypto_spawn_skcipher_alg(&ctx->enc);
 431
 432         ctx->reqoff = ALIGN(2 * auth->digestsize + auth_base->cra_alignmask,
 433                             auth_base->cra_alignmask + 1);
 434
 435         err = -ENAMETOOLONG;
 436         if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 437                      "authenc(%s,%s)", auth_base->cra_name,
 438                      enc->base.cra_name) >=
 439             CRYPTO_MAX_ALG_NAME)
 440                 goto err_drop_enc;
 441
 442         if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 443                      "authenc(%s,%s)", auth_base->cra_driver_name,
 444                      enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 445                 goto err_drop_enc;
 446
 447         inst->alg.base.cra_flags = (auth_base->cra_flags |
 448                                     enc->base.cra_flags) & CRYPTO_ALG_ASYNC;
 449         inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
 450                                       auth_base->cra_priority;
 451         inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
 452         inst->alg.base.cra_alignmask = auth_base->cra_alignmask |
 453                                        enc->base.cra_alignmask;
 454         inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
 455
 456         inst->alg.ivsize = crypto_skcipher_alg_ivsize(enc);
 457         inst->alg.chunksize = crypto_skcipher_alg_chunksize(enc);
 458         inst->alg.maxauthsize = auth->digestsize;
 459
 460         inst->alg.init = crypto_authenc_init_tfm;
 461         inst->alg.exit = crypto_authenc_exit_tfm;
 462
 463         inst->alg.setkey = crypto_authenc_setkey;
 464         inst->alg.encrypt = crypto_authenc_encrypt;
 465         inst->alg.decrypt = crypto_authenc_decrypt;
 466
 467         inst->free = crypto_authenc_free;
 468
 469         err = aead_register_instance(tmpl, inst);
 470         if (err)
 471                 goto err_drop_enc;
 472
 473 out:
 474         crypto_mod_put(auth_base);
 475         return err;
 476
 477 err_drop_enc:
 478         crypto_drop_skcipher(&ctx->enc);
 479 err_drop_auth:
 480         crypto_drop_ahash(&ctx->auth);
 481 err_free_inst:
 482         kfree(inst);
 483 out_put_auth:
 484         goto out;
 485 }
 486
 487 static struct crypto_template crypto_authenc_tmpl = {
 488         .name = "authenc",
 489         .create = crypto_authenc_create,
 490         .module = THIS_MODULE,
 491 };
 492
 493 static int __init crypto_authenc_module_init(void)
 494 {
 495         return crypto_register_template(&crypto_authenc_tmpl);
 496 }
 497
 498 static void __exit crypto_authenc_module_exit(void)
 499 {
 500         crypto_unregister_template(&crypto_authenc_tmpl);
 501 }
 502
 503 module_init(crypto_authenc_module_init);
 504 module_exit(crypto_authenc_module_exit);
 505
 506 MODULE_LICENSE("GPL");
 507 MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");
 508 MODULE_ALIAS_CRYPTO("authenc");