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_ablkcipher *enc;
  39         struct crypto_blkcipher *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_ablkcipher *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_ablkcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
  86         crypto_ablkcipher_set_flags(enc, crypto_aead_get_flags(authenc_esn) &
  87                                          CRYPTO_TFM_REQ_MASK);
  88         err = crypto_ablkcipher_setkey(enc, keys.enckey, keys.enckeylen);
  89         crypto_aead_set_flags(authenc_esn, crypto_ablkcipher_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         struct blkcipher_desc desc = {
 187                 .tfm = ctx->null,
 188         };
 189
 190         return crypto_blkcipher_encrypt(&desc, req->dst, req->src, len);
 191 }
 192
 193 static int crypto_authenc_esn_encrypt(struct aead_request *req)
 194 {
 195         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 196         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 197         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 198         struct ablkcipher_request *abreq = (void *)(areq_ctx->tail
 199                                                     + ctx->reqoff);
 200         struct crypto_ablkcipher *enc = ctx->enc;
 201         unsigned int assoclen = req->assoclen;
 202         unsigned int cryptlen = req->cryptlen;
 203         struct scatterlist *src, *dst;
 204         int err;
 205
 206         sg_init_table(areq_ctx->src, 2);
 207         src = scatterwalk_ffwd(areq_ctx->src, req->src, assoclen);
 208         dst = src;
 209
 210         if (req->src != req->dst) {
 211                 err = crypto_authenc_esn_copy(req, assoclen);
 212                 if (err)
 213                         return err;
 214
 215                 sg_init_table(areq_ctx->dst, 2);
 216                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, assoclen);
 217         }
 218
 219         ablkcipher_request_set_tfm(abreq, enc);
 220         ablkcipher_request_set_callback(abreq, aead_request_flags(req),
 221                                         crypto_authenc_esn_encrypt_done, req);
 222         ablkcipher_request_set_crypt(abreq, src, dst, cryptlen, req->iv);
 223
 224         err = crypto_ablkcipher_encrypt(abreq);
 225         if (err)
 226                 return err;
 227
 228         return crypto_authenc_esn_genicv(req, aead_request_flags(req));
 229 }
 230
 231 static int crypto_authenc_esn_decrypt_tail(struct aead_request *req,
 232                                            unsigned int flags)
 233 {
 234         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 235         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 236         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 237         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 238         struct ablkcipher_request *abreq = (void *)(areq_ctx->tail
 239                                                     + ctx->reqoff);
 240         struct crypto_ahash *auth = ctx->auth;
 241         u8 *ohash = PTR_ALIGN((u8 *)areq_ctx->tail,
 242                               crypto_ahash_alignmask(auth) + 1);
 243         unsigned int cryptlen = req->cryptlen - authsize;
 244         unsigned int assoclen = req->assoclen;
 245         struct scatterlist *dst = req->dst;
 246         u8 *ihash = ohash + crypto_ahash_digestsize(auth);
 247         u32 tmp[2];
 248
 249         if (!authsize)
 250                 goto decrypt;
 251
 252         /* Move high-order bits of sequence number back. */
 253         scatterwalk_map_and_copy(tmp, dst, 4, 4, 0);
 254         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 0);
 255         scatterwalk_map_and_copy(tmp, dst, 0, 8, 1);
 256
 257         if (crypto_memneq(ihash, ohash, authsize))
 258                 return -EBADMSG;
 259
 260 decrypt:
 261
 262         sg_init_table(areq_ctx->dst, 2);
 263         dst = scatterwalk_ffwd(areq_ctx->dst, dst, assoclen);
 264
 265         ablkcipher_request_set_tfm(abreq, ctx->enc);
 266         ablkcipher_request_set_callback(abreq, flags,
 267                                         req->base.complete, req->base.data);
 268         ablkcipher_request_set_crypt(abreq, dst, dst, cryptlen, req->iv);
 269
 270         return crypto_ablkcipher_decrypt(abreq);
 271 }
 272
 273 static void authenc_esn_verify_ahash_done(struct crypto_async_request *areq,
 274                                           int err)
 275 {
 276         struct aead_request *req = areq->data;
 277
 278         err = err ?: crypto_authenc_esn_decrypt_tail(req, 0);
 279         aead_request_complete(req, err);
 280 }
 281
 282 static int crypto_authenc_esn_decrypt(struct aead_request *req)
 283 {
 284         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 285         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 286         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 287         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
 288         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 289         struct crypto_ahash *auth = ctx->auth;
 290         u8 *ohash = PTR_ALIGN((u8 *)areq_ctx->tail,
 291                               crypto_ahash_alignmask(auth) + 1);
 292         unsigned int assoclen = req->assoclen;
 293         unsigned int cryptlen = req->cryptlen;
 294         u8 *ihash = ohash + crypto_ahash_digestsize(auth);
 295         struct scatterlist *dst = req->dst;
 296         u32 tmp[2];
 297         int err;
 298
 299         cryptlen -= authsize;
 300
 301         if (req->src != dst) {
 302                 err = crypto_authenc_esn_copy(req, assoclen + cryptlen);
 303                 if (err)
 304                         return err;
 305         }
 306
 307         scatterwalk_map_and_copy(ihash, req->src, assoclen + cryptlen,
 308                                  authsize, 0);
 309
 310         if (!authsize)
 311                 goto tail;
 312
 313         /* Move high-order bits of sequence number to the end. */
 314         scatterwalk_map_and_copy(tmp, dst, 0, 8, 0);
 315         scatterwalk_map_and_copy(tmp, dst, 4, 4, 1);
 316         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 1);
 317
 318         sg_init_table(areq_ctx->dst, 2);
 319         dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
 320
 321         ahash_request_set_tfm(ahreq, auth);
 322         ahash_request_set_crypt(ahreq, dst, ohash, assoclen + cryptlen);
 323         ahash_request_set_callback(ahreq, aead_request_flags(req),
 324                                    authenc_esn_verify_ahash_done, req);
 325
 326         err = crypto_ahash_digest(ahreq);
 327         if (err)
 328                 return err;
 329
 330 tail:
 331         return crypto_authenc_esn_decrypt_tail(req, aead_request_flags(req));
 332 }
 333
 334 static int crypto_authenc_esn_init_tfm(struct crypto_aead *tfm)
 335 {
 336         struct aead_instance *inst = aead_alg_instance(tfm);
 337         struct authenc_esn_instance_ctx *ictx = aead_instance_ctx(inst);
 338         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(tfm);
 339         struct crypto_ahash *auth;
 340         struct crypto_ablkcipher *enc;
 341         struct crypto_blkcipher *null;
 342         int err;
 343
 344         auth = crypto_spawn_ahash(&ictx->auth);
 345         if (IS_ERR(auth))
 346                 return PTR_ERR(auth);
 347
 348         enc = crypto_spawn_skcipher(&ictx->enc);
 349         err = PTR_ERR(enc);
 350         if (IS_ERR(enc))
 351                 goto err_free_ahash;
 352
 353         null = crypto_get_default_null_skcipher();
 354         err = PTR_ERR(null);
 355         if (IS_ERR(null))
 356                 goto err_free_skcipher;
 357
 358         ctx->auth = auth;
 359         ctx->enc = enc;
 360         ctx->null = null;
 361
 362         ctx->reqoff = ALIGN(2 * crypto_ahash_digestsize(auth),
 363                             crypto_ahash_alignmask(auth) + 1);
 364
 365         crypto_aead_set_reqsize(
 366                 tfm,
 367                 sizeof(struct authenc_esn_request_ctx) +
 368                 ctx->reqoff +
 369                 max_t(unsigned int,
 370                         crypto_ahash_reqsize(auth) +
 371                         sizeof(struct ahash_request),
 372                         sizeof(struct skcipher_givcrypt_request) +
 373                         crypto_ablkcipher_reqsize(enc)));
 374
 375         return 0;
 376
 377 err_free_skcipher:
 378         crypto_free_ablkcipher(enc);
 379 err_free_ahash:
 380         crypto_free_ahash(auth);
 381         return err;
 382 }
 383
 384 static void crypto_authenc_esn_exit_tfm(struct crypto_aead *tfm)
 385 {
 386         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(tfm);
 387
 388         crypto_free_ahash(ctx->auth);
 389         crypto_free_ablkcipher(ctx->enc);
 390         crypto_put_default_null_skcipher();
 391 }
 392
 393 static void crypto_authenc_esn_free(struct aead_instance *inst)
 394 {
 395         struct authenc_esn_instance_ctx *ctx = aead_instance_ctx(inst);
 396
 397         crypto_drop_skcipher(&ctx->enc);
 398         crypto_drop_ahash(&ctx->auth);
 399         kfree(inst);
 400 }
 401
 402 static int crypto_authenc_esn_create(struct crypto_template *tmpl,
 403                                      struct rtattr **tb)
 404 {
 405         struct crypto_attr_type *algt;
 406         struct aead_instance *inst;
 407         struct hash_alg_common *auth;
 408         struct crypto_alg *auth_base;
 409         struct crypto_alg *enc;
 410         struct authenc_esn_instance_ctx *ctx;
 411         const char *enc_name;
 412         int err;
 413
 414         algt = crypto_get_attr_type(tb);
 415         if (IS_ERR(algt))
 416                 return PTR_ERR(algt);
 417
 418         if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
 419                 return -EINVAL;
 420
 421         auth = ahash_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
 422                                CRYPTO_ALG_TYPE_AHASH_MASK);
 423         if (IS_ERR(auth))
 424                 return PTR_ERR(auth);
 425
 426         auth_base = &auth->base;
 427
 428         enc_name = crypto_attr_alg_name(tb[2]);
 429         err = PTR_ERR(enc_name);
 430         if (IS_ERR(enc_name))
 431                 goto out_put_auth;
 432
 433         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 434         err = -ENOMEM;
 435         if (!inst)
 436                 goto out_put_auth;
 437
 438         ctx = aead_instance_ctx(inst);
 439
 440         err = crypto_init_ahash_spawn(&ctx->auth, auth,
 441                                       aead_crypto_instance(inst));
 442         if (err)
 443                 goto err_free_inst;
 444
 445         crypto_set_skcipher_spawn(&ctx->enc, aead_crypto_instance(inst));
 446         err = crypto_grab_skcipher(&ctx->enc, enc_name, 0,
 447                                    crypto_requires_sync(algt->type,
 448                                                         algt->mask));
 449         if (err)
 450                 goto err_drop_auth;
 451
 452         enc = crypto_skcipher_spawn_alg(&ctx->enc);
 453
 454         err = -ENAMETOOLONG;
 455         if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 456                      "authencesn(%s,%s)", auth_base->cra_name,
 457                      enc->cra_name) >= CRYPTO_MAX_ALG_NAME)
 458                 goto err_drop_enc;
 459
 460         if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 461                      "authencesn(%s,%s)", auth_base->cra_driver_name,
 462                      enc->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 463                 goto err_drop_enc;
 464
 465         inst->alg.base.cra_flags = enc->cra_flags & CRYPTO_ALG_ASYNC;
 466         inst->alg.base.cra_priority = enc->cra_priority * 10 +
 467                                       auth_base->cra_priority;
 468         inst->alg.base.cra_blocksize = enc->cra_blocksize;
 469         inst->alg.base.cra_alignmask = auth_base->cra_alignmask |
 470                                        enc->cra_alignmask;
 471         inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_esn_ctx);
 472
 473         inst->alg.ivsize = enc->cra_ablkcipher.ivsize;
 474         inst->alg.maxauthsize = auth->digestsize;
 475
 476         inst->alg.init = crypto_authenc_esn_init_tfm;
 477         inst->alg.exit = crypto_authenc_esn_exit_tfm;
 478
 479         inst->alg.setkey = crypto_authenc_esn_setkey;
 480         inst->alg.setauthsize = crypto_authenc_esn_setauthsize;
 481         inst->alg.encrypt = crypto_authenc_esn_encrypt;
 482         inst->alg.decrypt = crypto_authenc_esn_decrypt;
 483
 484         inst->free = crypto_authenc_esn_free,
 485
 486         err = aead_register_instance(tmpl, inst);
 487         if (err)
 488                 goto err_drop_enc;
 489
 490 out:
 491         crypto_mod_put(auth_base);
 492         return err;
 493
 494 err_drop_enc:
 495         crypto_drop_skcipher(&ctx->enc);
 496 err_drop_auth:
 497         crypto_drop_ahash(&ctx->auth);
 498 err_free_inst:
 499         kfree(inst);
 500 out_put_auth:
 501         goto out;
 502 }
 503
 504 static struct crypto_template crypto_authenc_esn_tmpl = {
 505         .name = "authencesn",
 506         .create = crypto_authenc_esn_create,
 507         .module = THIS_MODULE,
 508 };
 509
 510 static int __init crypto_authenc_esn_module_init(void)
 511 {
 512         return crypto_register_template(&crypto_authenc_esn_tmpl);
 513 }
 514
 515 static void __exit crypto_authenc_esn_module_exit(void)
 516 {
 517         crypto_unregister_template(&crypto_authenc_esn_tmpl);
 518 }
 519
 520 module_init(crypto_authenc_esn_module_init);
 521 module_exit(crypto_authenc_esn_module_exit);
 522
 523 MODULE_LICENSE("GPL");
 524 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
 525 MODULE_DESCRIPTION("AEAD wrapper for IPsec with extended sequence numbers");
 526 MODULE_ALIAS_CRYPTO("authencesn");