crypto/authencesn.c

   1 /*
   2  * authencesn.c - AEAD wrapper for IPsec with extended sequence numbers,
   3  *                 derived from authenc.c
   4  *
   5  * Copyright (C) 2010 secunet Security Networks AG
   6  * Copyright (C) 2010 Steffen Klassert <steffen.klassert@secunet.com>
   7  * Copyright (c) 2015 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/hash.h>
  18 #include <crypto/internal/skcipher.h>
  19 #include <crypto/authenc.h>
  20 #include <crypto/null.h>
  21 #include <crypto/scatterwalk.h>
  22 #include <linux/err.h>
  23 #include <linux/init.h>
  24 #include <linux/kernel.h>
  25 #include <linux/module.h>
  26 #include <linux/rtnetlink.h>
  27 #include <linux/slab.h>
  28 #include <linux/spinlock.h>
  29
  30 struct authenc_esn_instance_ctx {
  31         struct crypto_ahash_spawn auth;
  32         struct crypto_skcipher_spawn enc;
  33 };
  34
  35 struct crypto_authenc_esn_ctx {
  36         unsigned int reqoff;
  37         struct crypto_ahash *auth;
  38         struct crypto_skcipher *enc;
  39         struct crypto_skcipher *null;
  40 };
  41
  42 struct authenc_esn_request_ctx {
  43         struct scatterlist src[2];
  44         struct scatterlist dst[2];
  45         char tail[];
  46 };
  47
  48 static void authenc_esn_request_complete(struct aead_request *req, int err)
  49 {
  50         if (err != -EINPROGRESS)
  51                 aead_request_complete(req, err);
  52 }
  53
  54 static int crypto_authenc_esn_setauthsize(struct crypto_aead *authenc_esn,
  55                                           unsigned int authsize)
  56 {
  57         if (authsize > 0 && authsize < 4)
  58                 return -EINVAL;
  59
  60         return 0;
  61 }
  62
  63 static int crypto_authenc_esn_setkey(struct crypto_aead *authenc_esn, const u8 *key,
  64                                      unsigned int keylen)
  65 {
  66         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
  67         struct crypto_ahash *auth = ctx->auth;
  68         struct crypto_skcipher *enc = ctx->enc;
  69         struct crypto_authenc_keys keys;
  70         int err = -EINVAL;
  71
  72         if (crypto_authenc_extractkeys(&keys, key, keylen) != 0)
  73                 goto badkey;
  74
  75         crypto_ahash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
  76         crypto_ahash_set_flags(auth, crypto_aead_get_flags(authenc_esn) &
  77                                      CRYPTO_TFM_REQ_MASK);
  78         err = crypto_ahash_setkey(auth, keys.authkey, keys.authkeylen);
  79         crypto_aead_set_flags(authenc_esn, crypto_ahash_get_flags(auth) &
  80                                            CRYPTO_TFM_RES_MASK);
  81
  82         if (err)
  83                 goto out;
  84
  85         crypto_skcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
  86         crypto_skcipher_set_flags(enc, crypto_aead_get_flags(authenc_esn) &
  87                                          CRYPTO_TFM_REQ_MASK);
  88         err = crypto_skcipher_setkey(enc, keys.enckey, keys.enckeylen);
  89         crypto_aead_set_flags(authenc_esn, crypto_skcipher_get_flags(enc) &
  90                                            CRYPTO_TFM_RES_MASK);
  91
  92 out:
  93         memzero_explicit(&keys, sizeof(keys));
  94         return err;
  95
  96 badkey:
  97         crypto_aead_set_flags(authenc_esn, CRYPTO_TFM_RES_BAD_KEY_LEN);
  98         goto out;
  99 }
 100
 101 static int crypto_authenc_esn_genicv_tail(struct aead_request *req,
 102                                           unsigned int flags)
 103 {
 104         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 105         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 106         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 107         struct crypto_ahash *auth = ctx->auth;
 108         u8 *hash = PTR_ALIGN((u8 *)areq_ctx->tail,
 109                              crypto_ahash_alignmask(auth) + 1);
 110         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 111         unsigned int assoclen = req->assoclen;
 112         unsigned int cryptlen = req->cryptlen;
 113         struct scatterlist *dst = req->dst;
 114         u32 tmp[2];
 115
 116         /* Move high-order bits of sequence number back. */
 117         scatterwalk_map_and_copy(tmp, dst, 4, 4, 0);
 118         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 0);
 119         scatterwalk_map_and_copy(tmp, dst, 0, 8, 1);
 120
 121         scatterwalk_map_and_copy(hash, dst, assoclen + cryptlen, authsize, 1);
 122         return 0;
 123 }
 124
 125 static void authenc_esn_geniv_ahash_done(struct crypto_async_request *areq,
 126                                          int err)
 127 {
 128         struct aead_request *req = areq->data;
 129
 130         err = err ?: crypto_authenc_esn_genicv_tail(req, 0);
 131         aead_request_complete(req, err);
 132 }
 133
 134 static int crypto_authenc_esn_genicv(struct aead_request *req,
 135                                      unsigned int flags)
 136 {
 137         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 138         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 139         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 140         struct crypto_ahash *auth = ctx->auth;
 141         u8 *hash = PTR_ALIGN((u8 *)areq_ctx->tail,
 142                              crypto_ahash_alignmask(auth) + 1);
 143         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
 144         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 145         unsigned int assoclen = req->assoclen;
 146         unsigned int cryptlen = req->cryptlen;
 147         struct scatterlist *dst = req->dst;
 148         u32 tmp[2];
 149
 150         if (!authsize)
 151                 return 0;
 152
 153         /* Move high-order bits of sequence number to the end. */
 154         scatterwalk_map_and_copy(tmp, dst, 0, 8, 0);
 155         scatterwalk_map_and_copy(tmp, dst, 4, 4, 1);
 156         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 1);
 157
 158         sg_init_table(areq_ctx->dst, 2);
 159         dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
 160
 161         ahash_request_set_tfm(ahreq, auth);
 162         ahash_request_set_crypt(ahreq, dst, hash, assoclen + cryptlen);
 163         ahash_request_set_callback(ahreq, flags,
 164                                    authenc_esn_geniv_ahash_done, req);
 165
 166         return crypto_ahash_digest(ahreq) ?:
 167                crypto_authenc_esn_genicv_tail(req, aead_request_flags(req));
 168 }
 169
 170
 171 static void crypto_authenc_esn_encrypt_done(struct crypto_async_request *req,
 172                                             int err)
 173 {
 174         struct aead_request *areq = req->data;
 175
 176         if (!err)
 177                 err = crypto_authenc_esn_genicv(areq, 0);
 178
 179         authenc_esn_request_complete(areq, err);
 180 }
 181
 182 static int crypto_authenc_esn_copy(struct aead_request *req, unsigned int len)
 183 {
 184         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 185         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 186         SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);
 187
 188         skcipher_request_set_tfm(skreq, ctx->null);
 189         skcipher_request_set_callback(skreq, aead_request_flags(req),
 190                                       NULL, NULL);
 191         skcipher_request_set_crypt(skreq, req->src, req->dst, len, NULL);
 192
 193         return crypto_skcipher_encrypt(skreq);
 194 }
 195
 196 static int crypto_authenc_esn_encrypt(struct aead_request *req)
 197 {
 198         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 199         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 200         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 201         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 202                                                   ctx->reqoff);
 203         struct crypto_skcipher *enc = ctx->enc;
 204         unsigned int assoclen = req->assoclen;
 205         unsigned int cryptlen = req->cryptlen;
 206         struct scatterlist *src, *dst;
 207         int err;
 208
 209         sg_init_table(areq_ctx->src, 2);
 210         src = scatterwalk_ffwd(areq_ctx->src, req->src, assoclen);
 211         dst = src;
 212
 213         if (req->src != req->dst) {
 214                 err = crypto_authenc_esn_copy(req, assoclen);
 215                 if (err)
 216                         return err;
 217
 218                 sg_init_table(areq_ctx->dst, 2);
 219                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, assoclen);
 220         }
 221
 222         skcipher_request_set_tfm(skreq, enc);
 223         skcipher_request_set_callback(skreq, aead_request_flags(req),
 224                                       crypto_authenc_esn_encrypt_done, req);
 225         skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
 226
 227         err = crypto_skcipher_encrypt(skreq);
 228         if (err)
 229                 return err;
 230
 231         return crypto_authenc_esn_genicv(req, aead_request_flags(req));
 232 }
 233
 234 static int crypto_authenc_esn_decrypt_tail(struct aead_request *req,
 235                                            unsigned int flags)
 236 {
 237         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 238         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 239         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 240         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 241         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 242                                                   ctx->reqoff);
 243         struct crypto_ahash *auth = ctx->auth;
 244         u8 *ohash = PTR_ALIGN((u8 *)areq_ctx->tail,
 245                               crypto_ahash_alignmask(auth) + 1);
 246         unsigned int cryptlen = req->cryptlen - authsize;
 247         unsigned int assoclen = req->assoclen;
 248         struct scatterlist *dst = req->dst;
 249         u8 *ihash = ohash + crypto_ahash_digestsize(auth);
 250         u32 tmp[2];
 251
 252         if (!authsize)
 253                 goto decrypt;
 254
 255         /* Move high-order bits of sequence number back. */
 256         scatterwalk_map_and_copy(tmp, dst, 4, 4, 0);
 257         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 0);
 258         scatterwalk_map_and_copy(tmp, dst, 0, 8, 1);
 259
 260         if (crypto_memneq(ihash, ohash, authsize))
 261                 return -EBADMSG;
 262
 263 decrypt:
 264
 265         sg_init_table(areq_ctx->dst, 2);
 266         dst = scatterwalk_ffwd(areq_ctx->dst, dst, assoclen);
 267
 268         skcipher_request_set_tfm(skreq, ctx->enc);
 269         skcipher_request_set_callback(skreq, flags,
 270                                       req->base.complete, req->base.data);
 271         skcipher_request_set_crypt(skreq, dst, dst, cryptlen, req->iv);
 272
 273         return crypto_skcipher_decrypt(skreq);
 274 }
 275
 276 static void authenc_esn_verify_ahash_done(struct crypto_async_request *areq,
 277                                           int err)
 278 {
 279         struct aead_request *req = areq->data;
 280
 281         err = err ?: crypto_authenc_esn_decrypt_tail(req, 0);
 282         aead_request_complete(req, err);
 283 }
 284
 285 static int crypto_authenc_esn_decrypt(struct aead_request *req)
 286 {
 287         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 288         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 289         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 290         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
 291         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 292         struct crypto_ahash *auth = ctx->auth;
 293         u8 *ohash = PTR_ALIGN((u8 *)areq_ctx->tail,
 294                               crypto_ahash_alignmask(auth) + 1);
 295         unsigned int assoclen = req->assoclen;
 296         unsigned int cryptlen = req->cryptlen;
 297         u8 *ihash = ohash + crypto_ahash_digestsize(auth);
 298         struct scatterlist *dst = req->dst;
 299         u32 tmp[2];
 300         int err;
 301
 302         cryptlen -= authsize;
 303
 304         if (req->src != dst) {
 305                 err = crypto_authenc_esn_copy(req, assoclen + cryptlen);
 306                 if (err)
 307                         return err;
 308         }
 309
 310         scatterwalk_map_and_copy(ihash, req->src, assoclen + cryptlen,
 311                                  authsize, 0);
 312
 313         if (!authsize)
 314                 goto tail;
 315
 316         /* Move high-order bits of sequence number to the end. */
 317         scatterwalk_map_and_copy(tmp, dst, 0, 8, 0);
 318         scatterwalk_map_and_copy(tmp, dst, 4, 4, 1);
 319         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 1);
 320
 321         sg_init_table(areq_ctx->dst, 2);
 322         dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
 323
 324         ahash_request_set_tfm(ahreq, auth);
 325         ahash_request_set_crypt(ahreq, dst, ohash, assoclen + cryptlen);
 326         ahash_request_set_callback(ahreq, aead_request_flags(req),
 327                                    authenc_esn_verify_ahash_done, req);
 328
 329         err = crypto_ahash_digest(ahreq);
 330         if (err)
 331                 return err;
 332
 333 tail:
 334         return crypto_authenc_esn_decrypt_tail(req, aead_request_flags(req));
 335 }
 336
 337 static int crypto_authenc_esn_init_tfm(struct crypto_aead *tfm)
 338 {
 339         struct aead_instance *inst = aead_alg_instance(tfm);
 340         struct authenc_esn_instance_ctx *ictx = aead_instance_ctx(inst);
 341         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(tfm);
 342         struct crypto_ahash *auth;
 343         struct crypto_skcipher *enc;
 344         struct crypto_skcipher *null;
 345         int err;
 346
 347         auth = crypto_spawn_ahash(&ictx->auth);
 348         if (IS_ERR(auth))
 349                 return PTR_ERR(auth);
 350
 351         enc = crypto_spawn_skcipher(&ictx->enc);
 352         err = PTR_ERR(enc);
 353         if (IS_ERR(enc))
 354                 goto err_free_ahash;
 355
 356         null = crypto_get_default_null_skcipher();
 357         err = PTR_ERR(null);
 358         if (IS_ERR(null))
 359                 goto err_free_skcipher;
 360
 361         ctx->auth = auth;
 362         ctx->enc = enc;
 363         ctx->null = null;
 364
 365         ctx->reqoff = ALIGN(2 * crypto_ahash_digestsize(auth),
 366                             crypto_ahash_alignmask(auth) + 1);
 367
 368         crypto_aead_set_reqsize(
 369                 tfm,
 370                 sizeof(struct authenc_esn_request_ctx) +
 371                 ctx->reqoff +
 372                 max_t(unsigned int,
 373                       crypto_ahash_reqsize(auth) +
 374                       sizeof(struct ahash_request),
 375                       sizeof(struct skcipher_request) +
 376                       crypto_skcipher_reqsize(enc)));
 377
 378         return 0;
 379
 380 err_free_skcipher:
 381         crypto_free_skcipher(enc);
 382 err_free_ahash:
 383         crypto_free_ahash(auth);
 384         return err;
 385 }
 386
 387 static void crypto_authenc_esn_exit_tfm(struct crypto_aead *tfm)
 388 {
 389         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(tfm);
 390
 391         crypto_free_ahash(ctx->auth);
 392         crypto_free_skcipher(ctx->enc);
 393         crypto_put_default_null_skcipher();
 394 }
 395
 396 static void crypto_authenc_esn_free(struct aead_instance *inst)
 397 {
 398         struct authenc_esn_instance_ctx *ctx = aead_instance_ctx(inst);
 399
 400         crypto_drop_skcipher(&ctx->enc);
 401         crypto_drop_ahash(&ctx->auth);
 402         kfree(inst);
 403 }
 404
 405 static int crypto_authenc_esn_create(struct crypto_template *tmpl,
 406                                      struct rtattr **tb)
 407 {
 408         struct crypto_attr_type *algt;
 409         struct aead_instance *inst;
 410         struct hash_alg_common *auth;
 411         struct crypto_alg *auth_base;
 412         struct skcipher_alg *enc;
 413         struct authenc_esn_instance_ctx *ctx;
 414         const char *enc_name;
 415         int err;
 416
 417         algt = crypto_get_attr_type(tb);
 418         if (IS_ERR(algt))
 419                 return PTR_ERR(algt);
 420
 421         if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
 422                 return -EINVAL;
 423
 424         auth = ahash_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
 425                               CRYPTO_ALG_TYPE_AHASH_MASK |
 426                               crypto_requires_sync(algt->type, algt->mask));
 427         if (IS_ERR(auth))
 428                 return PTR_ERR(auth);
 429
 430         auth_base = &auth->base;
 431
 432         enc_name = crypto_attr_alg_name(tb[2]);
 433         err = PTR_ERR(enc_name);
 434         if (IS_ERR(enc_name))
 435                 goto out_put_auth;
 436
 437         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 438         err = -ENOMEM;
 439         if (!inst)
 440                 goto out_put_auth;
 441
 442         ctx = aead_instance_ctx(inst);
 443
 444         err = crypto_init_ahash_spawn(&ctx->auth, auth,
 445                                       aead_crypto_instance(inst));
 446         if (err)
 447                 goto err_free_inst;
 448
 449         crypto_set_skcipher_spawn(&ctx->enc, aead_crypto_instance(inst));
 450         err = crypto_grab_skcipher(&ctx->enc, enc_name, 0,
 451                                    crypto_requires_sync(algt->type,
 452                                                         algt->mask));
 453         if (err)
 454                 goto err_drop_auth;
 455
 456         enc = crypto_spawn_skcipher_alg(&ctx->enc);
 457
 458         err = -ENAMETOOLONG;
 459         if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 460                      "authencesn(%s,%s)", auth_base->cra_name,
 461                      enc->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
 462                 goto err_drop_enc;
 463
 464         if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 465                      "authencesn(%s,%s)", auth_base->cra_driver_name,
 466                      enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 467                 goto err_drop_enc;
 468
 469         inst->alg.base.cra_flags = (auth_base->cra_flags |
 470                                     enc->base.cra_flags) & CRYPTO_ALG_ASYNC;
 471         inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
 472                                       auth_base->cra_priority;
 473         inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
 474         inst->alg.base.cra_alignmask = auth_base->cra_alignmask |
 475                                        enc->base.cra_alignmask;
 476         inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_esn_ctx);
 477
 478         inst->alg.ivsize = crypto_skcipher_alg_ivsize(enc);
 479         inst->alg.chunksize = crypto_skcipher_alg_chunksize(enc);
 480         inst->alg.maxauthsize = auth->digestsize;
 481
 482         inst->alg.init = crypto_authenc_esn_init_tfm;
 483         inst->alg.exit = crypto_authenc_esn_exit_tfm;
 484
 485         inst->alg.setkey = crypto_authenc_esn_setkey;
 486         inst->alg.setauthsize = crypto_authenc_esn_setauthsize;
 487         inst->alg.encrypt = crypto_authenc_esn_encrypt;
 488         inst->alg.decrypt = crypto_authenc_esn_decrypt;
 489
 490         inst->free = crypto_authenc_esn_free,
 491
 492         err = aead_register_instance(tmpl, inst);
 493         if (err)
 494                 goto err_drop_enc;
 495
 496 out:
 497         crypto_mod_put(auth_base);
 498         return err;
 499
 500 err_drop_enc:
 501         crypto_drop_skcipher(&ctx->enc);
 502 err_drop_auth:
 503         crypto_drop_ahash(&ctx->auth);
 504 err_free_inst:
 505         kfree(inst);
 506 out_put_auth:
 507         goto out;
 508 }
 509
 510 static struct crypto_template crypto_authenc_esn_tmpl = {
 511         .name = "authencesn",
 512         .create = crypto_authenc_esn_create,
 513         .module = THIS_MODULE,
 514 };
 515
 516 static int __init crypto_authenc_esn_module_init(void)
 517 {
 518         return crypto_register_template(&crypto_authenc_esn_tmpl);
 519 }
 520
 521 static void __exit crypto_authenc_esn_module_exit(void)
 522 {
 523         crypto_unregister_template(&crypto_authenc_esn_tmpl);
 524 }
 525
 526 module_init(crypto_authenc_esn_module_init);
 527 module_exit(crypto_authenc_esn_module_exit);
 528
 529 MODULE_LICENSE("GPL");
 530 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
 531 MODULE_DESCRIPTION("AEAD wrapper for IPsec with extended sequence numbers");
 532 MODULE_ALIAS_CRYPTO("authencesn");