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_ablkcipher *enc;
  36         struct crypto_blkcipher *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_ablkcipher *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_ablkcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
 104         crypto_ablkcipher_set_flags(enc, crypto_aead_get_flags(authenc) &
 105                                          CRYPTO_TFM_REQ_MASK);
 106         err = crypto_ablkcipher_setkey(enc, keys.enckey, keys.enckeylen);
 107         crypto_aead_set_flags(authenc, crypto_ablkcipher_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         struct blkcipher_desc desc = {
 188                 .tfm = ctx->null,
 189         };
 190
 191         return crypto_blkcipher_encrypt(&desc, req->dst, req->src,
 192                                         req->assoclen);
 193 }
 194
 195 static int crypto_authenc_encrypt(struct aead_request *req)
 196 {
 197         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 198         struct aead_instance *inst = aead_alg_instance(authenc);
 199         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 200         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 201         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 202         struct crypto_ablkcipher *enc = ctx->enc;
 203         unsigned int cryptlen = req->cryptlen;
 204         struct ablkcipher_request *abreq = (void *)(areq_ctx->tail +
 205                                                     ictx->reqoff);
 206         struct scatterlist *src, *dst;
 207         int err;
 208
 209         src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
 210         dst = src;
 211
 212         if (req->src != req->dst) {
 213                 err = crypto_authenc_copy_assoc(req);
 214                 if (err)
 215                         return err;
 216
 217                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
 218         }
 219
 220         ablkcipher_request_set_tfm(abreq, enc);
 221         ablkcipher_request_set_callback(abreq, aead_request_flags(req),
 222                                         crypto_authenc_encrypt_done, req);
 223         ablkcipher_request_set_crypt(abreq, src, dst, cryptlen, req->iv);
 224
 225         err = crypto_ablkcipher_encrypt(abreq);
 226         if (err)
 227                 return err;
 228
 229         return crypto_authenc_genicv(req, aead_request_flags(req));
 230 }
 231
 232 static int crypto_authenc_decrypt_tail(struct aead_request *req,
 233                                        unsigned int flags)
 234 {
 235         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 236         struct aead_instance *inst = aead_alg_instance(authenc);
 237         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 238         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 239         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 240         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 241         struct ablkcipher_request *abreq = (void *)(areq_ctx->tail +
 242                                                     ictx->reqoff);
 243         unsigned int authsize = crypto_aead_authsize(authenc);
 244         u8 *ihash = ahreq->result + authsize;
 245         struct scatterlist *src, *dst;
 246
 247         scatterwalk_map_and_copy(ihash, req->src, ahreq->nbytes, authsize, 0);
 248
 249         if (crypto_memneq(ihash, ahreq->result, authsize))
 250                 return -EBADMSG;
 251
 252         src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
 253         dst = src;
 254
 255         if (req->src != req->dst)
 256                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
 257
 258         ablkcipher_request_set_tfm(abreq, ctx->enc);
 259         ablkcipher_request_set_callback(abreq, aead_request_flags(req),
 260                                         req->base.complete, req->base.data);
 261         ablkcipher_request_set_crypt(abreq, src, dst,
 262                                      req->cryptlen - authsize, req->iv);
 263
 264         return crypto_ablkcipher_decrypt(abreq);
 265 }
 266
 267 static void authenc_verify_ahash_done(struct crypto_async_request *areq,
 268                                       int err)
 269 {
 270         struct aead_request *req = areq->data;
 271
 272         if (err)
 273                 goto out;
 274
 275         err = crypto_authenc_decrypt_tail(req, 0);
 276
 277 out:
 278         authenc_request_complete(req, err);
 279 }
 280
 281 static int crypto_authenc_decrypt(struct aead_request *req)
 282 {
 283         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 284         unsigned int authsize = crypto_aead_authsize(authenc);
 285         struct aead_instance *inst = aead_alg_instance(authenc);
 286         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 287         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 288         struct crypto_ahash *auth = ctx->auth;
 289         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 290         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 291         u8 *hash = areq_ctx->tail;
 292         int err;
 293
 294         hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
 295                            crypto_ahash_alignmask(auth) + 1);
 296
 297         ahash_request_set_tfm(ahreq, auth);
 298         ahash_request_set_crypt(ahreq, req->src, hash,
 299                                 req->assoclen + req->cryptlen - authsize);
 300         ahash_request_set_callback(ahreq, aead_request_flags(req),
 301                                    authenc_verify_ahash_done, req);
 302
 303         err = crypto_ahash_digest(ahreq);
 304         if (err)
 305                 return err;
 306
 307         return crypto_authenc_decrypt_tail(req, aead_request_flags(req));
 308 }
 309
 310 static int crypto_authenc_init_tfm(struct crypto_aead *tfm)
 311 {
 312         struct aead_instance *inst = aead_alg_instance(tfm);
 313         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 314         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
 315         struct crypto_ahash *auth;
 316         struct crypto_ablkcipher *enc;
 317         struct crypto_blkcipher *null;
 318         int err;
 319
 320         auth = crypto_spawn_ahash(&ictx->auth);
 321         if (IS_ERR(auth))
 322                 return PTR_ERR(auth);
 323
 324         enc = crypto_spawn_skcipher(&ictx->enc);
 325         err = PTR_ERR(enc);
 326         if (IS_ERR(enc))
 327                 goto err_free_ahash;
 328
 329         null = crypto_get_default_null_skcipher();
 330         err = PTR_ERR(null);
 331         if (IS_ERR(null))
 332                 goto err_free_skcipher;
 333
 334         ctx->auth = auth;
 335         ctx->enc = enc;
 336         ctx->null = null;
 337
 338         crypto_aead_set_reqsize(
 339                 tfm,
 340                 sizeof(struct authenc_request_ctx) +
 341                 ictx->reqoff +
 342                 max_t(unsigned int,
 343                       crypto_ahash_reqsize(auth) +
 344                       sizeof(struct ahash_request),
 345                       sizeof(struct ablkcipher_request) +
 346                       crypto_ablkcipher_reqsize(enc)));
 347
 348         return 0;
 349
 350 err_free_skcipher:
 351         crypto_free_ablkcipher(enc);
 352 err_free_ahash:
 353         crypto_free_ahash(auth);
 354         return err;
 355 }
 356
 357 static void crypto_authenc_exit_tfm(struct crypto_aead *tfm)
 358 {
 359         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
 360
 361         crypto_free_ahash(ctx->auth);
 362         crypto_free_ablkcipher(ctx->enc);
 363         crypto_put_default_null_skcipher();
 364 }
 365
 366 static void crypto_authenc_free(struct aead_instance *inst)
 367 {
 368         struct authenc_instance_ctx *ctx = aead_instance_ctx(inst);
 369
 370         crypto_drop_skcipher(&ctx->enc);
 371         crypto_drop_ahash(&ctx->auth);
 372         kfree(inst);
 373 }
 374
 375 static int crypto_authenc_create(struct crypto_template *tmpl,
 376                                  struct rtattr **tb)
 377 {
 378         struct crypto_attr_type *algt;
 379         struct aead_instance *inst;
 380         struct hash_alg_common *auth;
 381         struct crypto_alg *auth_base;
 382         struct crypto_alg *enc;
 383         struct authenc_instance_ctx *ctx;
 384         const char *enc_name;
 385         int err;
 386
 387         algt = crypto_get_attr_type(tb);
 388         if (IS_ERR(algt))
 389                 return PTR_ERR(algt);
 390
 391         if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
 392                 return -EINVAL;
 393
 394         auth = ahash_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
 395                                CRYPTO_ALG_TYPE_AHASH_MASK);
 396         if (IS_ERR(auth))
 397                 return PTR_ERR(auth);
 398
 399         auth_base = &auth->base;
 400
 401         enc_name = crypto_attr_alg_name(tb[2]);
 402         err = PTR_ERR(enc_name);
 403         if (IS_ERR(enc_name))
 404                 goto out_put_auth;
 405
 406         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 407         err = -ENOMEM;
 408         if (!inst)
 409                 goto out_put_auth;
 410
 411         ctx = aead_instance_ctx(inst);
 412
 413         err = crypto_init_ahash_spawn(&ctx->auth, auth,
 414                                       aead_crypto_instance(inst));
 415         if (err)
 416                 goto err_free_inst;
 417
 418         crypto_set_skcipher_spawn(&ctx->enc, aead_crypto_instance(inst));
 419         err = crypto_grab_skcipher(&ctx->enc, enc_name, 0,
 420                                    crypto_requires_sync(algt->type,
 421                                                         algt->mask));
 422         if (err)
 423                 goto err_drop_auth;
 424
 425         enc = crypto_skcipher_spawn_alg(&ctx->enc);
 426
 427         ctx->reqoff = ALIGN(2 * auth->digestsize + auth_base->cra_alignmask,
 428                             auth_base->cra_alignmask + 1);
 429
 430         err = -ENAMETOOLONG;
 431         if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 432                      "authenc(%s,%s)", auth_base->cra_name, enc->cra_name) >=
 433             CRYPTO_MAX_ALG_NAME)
 434                 goto err_drop_enc;
 435
 436         if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 437                      "authenc(%s,%s)", auth_base->cra_driver_name,
 438                      enc->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 439                 goto err_drop_enc;
 440
 441         inst->alg.base.cra_flags = enc->cra_flags & CRYPTO_ALG_ASYNC;
 442         inst->alg.base.cra_priority = enc->cra_priority * 10 +
 443                                       auth_base->cra_priority;
 444         inst->alg.base.cra_blocksize = enc->cra_blocksize;
 445         inst->alg.base.cra_alignmask = auth_base->cra_alignmask |
 446                                        enc->cra_alignmask;
 447         inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
 448
 449         inst->alg.ivsize = enc->cra_ablkcipher.ivsize;
 450         inst->alg.maxauthsize = auth->digestsize;
 451
 452         inst->alg.init = crypto_authenc_init_tfm;
 453         inst->alg.exit = crypto_authenc_exit_tfm;
 454
 455         inst->alg.setkey = crypto_authenc_setkey;
 456         inst->alg.encrypt = crypto_authenc_encrypt;
 457         inst->alg.decrypt = crypto_authenc_decrypt;
 458
 459         inst->free = crypto_authenc_free;
 460
 461         err = aead_register_instance(tmpl, inst);
 462         if (err)
 463                 goto err_drop_enc;
 464
 465 out:
 466         crypto_mod_put(auth_base);
 467         return err;
 468
 469 err_drop_enc:
 470         crypto_drop_skcipher(&ctx->enc);
 471 err_drop_auth:
 472         crypto_drop_ahash(&ctx->auth);
 473 err_free_inst:
 474         kfree(inst);
 475 out_put_auth:
 476         goto out;
 477 }
 478
 479 static struct crypto_template crypto_authenc_tmpl = {
 480         .name = "authenc",
 481         .create = crypto_authenc_create,
 482         .module = THIS_MODULE,
 483 };
 484
 485 static int __init crypto_authenc_module_init(void)
 486 {
 487         return crypto_register_template(&crypto_authenc_tmpl);
 488 }
 489
 490 static void __exit crypto_authenc_module_exit(void)
 491 {
 492         crypto_unregister_template(&crypto_authenc_tmpl);
 493 }
 494
 495 module_init(crypto_authenc_module_init);
 496 module_exit(crypto_authenc_module_exit);
 497
 498 MODULE_LICENSE("GPL");
 499 MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");
 500 MODULE_ALIAS_CRYPTO("authenc");