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         return err;
  94
  95 badkey:
  96         crypto_aead_set_flags(authenc_esn, CRYPTO_TFM_RES_BAD_KEY_LEN);
  97         goto out;
  98 }
  99
 100 static int crypto_authenc_esn_genicv_tail(struct aead_request *req,
 101                                           unsigned int flags)
 102 {
 103         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 104         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 105         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 106         struct crypto_ahash *auth = ctx->auth;
 107         u8 *hash = PTR_ALIGN((u8 *)areq_ctx->tail,
 108                              crypto_ahash_alignmask(auth) + 1);
 109         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 110         unsigned int assoclen = req->assoclen;
 111         unsigned int cryptlen = req->cryptlen;
 112         struct scatterlist *dst = req->dst;
 113         u32 tmp[2];
 114
 115         /* Move high-order bits of sequence number back. */
 116         scatterwalk_map_and_copy(tmp, dst, 4, 4, 0);
 117         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 0);
 118         scatterwalk_map_and_copy(tmp, dst, 0, 8, 1);
 119
 120         scatterwalk_map_and_copy(hash, dst, assoclen + cryptlen, authsize, 1);
 121         return 0;
 122 }
 123
 124 static void authenc_esn_geniv_ahash_done(struct crypto_async_request *areq,
 125                                          int err)
 126 {
 127         struct aead_request *req = areq->data;
 128
 129         err = err ?: crypto_authenc_esn_genicv_tail(req, 0);
 130         aead_request_complete(req, err);
 131 }
 132
 133 static int crypto_authenc_esn_genicv(struct aead_request *req,
 134                                      unsigned int flags)
 135 {
 136         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 137         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 138         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 139         struct crypto_ahash *auth = ctx->auth;
 140         u8 *hash = PTR_ALIGN((u8 *)areq_ctx->tail,
 141                              crypto_ahash_alignmask(auth) + 1);
 142         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
 143         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 144         unsigned int assoclen = req->assoclen;
 145         unsigned int cryptlen = req->cryptlen;
 146         struct scatterlist *dst = req->dst;
 147         u32 tmp[2];
 148
 149         if (!authsize)
 150                 return 0;
 151
 152         /* Move high-order bits of sequence number to the end. */
 153         scatterwalk_map_and_copy(tmp, dst, 0, 8, 0);
 154         scatterwalk_map_and_copy(tmp, dst, 4, 4, 1);
 155         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 1);
 156
 157         sg_init_table(areq_ctx->dst, 2);
 158         dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
 159
 160         ahash_request_set_tfm(ahreq, auth);
 161         ahash_request_set_crypt(ahreq, dst, hash, assoclen + cryptlen);
 162         ahash_request_set_callback(ahreq, flags,
 163                                    authenc_esn_geniv_ahash_done, req);
 164
 165         return crypto_ahash_digest(ahreq) ?:
 166                crypto_authenc_esn_genicv_tail(req, aead_request_flags(req));
 167 }
 168
 169
 170 static void crypto_authenc_esn_encrypt_done(struct crypto_async_request *req,
 171                                             int err)
 172 {
 173         struct aead_request *areq = req->data;
 174
 175         if (!err)
 176                 err = crypto_authenc_esn_genicv(areq, 0);
 177
 178         authenc_esn_request_complete(areq, err);
 179 }
 180
 181 static int crypto_authenc_esn_copy(struct aead_request *req, unsigned int len)
 182 {
 183         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 184         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 185         struct blkcipher_desc desc = {
 186                 .tfm = ctx->null,
 187         };
 188
 189         return crypto_blkcipher_encrypt(&desc, req->dst, req->src, len);
 190 }
 191
 192 static int crypto_authenc_esn_encrypt(struct aead_request *req)
 193 {
 194         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 195         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 196         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 197         struct ablkcipher_request *abreq = (void *)(areq_ctx->tail
 198                                                     + ctx->reqoff);
 199         struct crypto_ablkcipher *enc = ctx->enc;
 200         unsigned int assoclen = req->assoclen;
 201         unsigned int cryptlen = req->cryptlen;
 202         struct scatterlist *src, *dst;
 203         int err;
 204
 205         sg_init_table(areq_ctx->src, 2);
 206         src = scatterwalk_ffwd(areq_ctx->src, req->src, assoclen);
 207         dst = src;
 208
 209         if (req->src != req->dst) {
 210                 err = crypto_authenc_esn_copy(req, assoclen);
 211                 if (err)
 212                         return err;
 213
 214                 sg_init_table(areq_ctx->dst, 2);
 215                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, assoclen);
 216         }
 217
 218         ablkcipher_request_set_tfm(abreq, enc);
 219         ablkcipher_request_set_callback(abreq, aead_request_flags(req),
 220                                         crypto_authenc_esn_encrypt_done, req);
 221         ablkcipher_request_set_crypt(abreq, src, dst, cryptlen, req->iv);
 222
 223         err = crypto_ablkcipher_encrypt(abreq);
 224         if (err)
 225                 return err;
 226
 227         return crypto_authenc_esn_genicv(req, aead_request_flags(req));
 228 }
 229
 230 static int crypto_authenc_esn_decrypt_tail(struct aead_request *req,
 231                                            unsigned int flags)
 232 {
 233         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 234         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 235         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 236         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 237         struct ablkcipher_request *abreq = (void *)(areq_ctx->tail
 238                                                     + ctx->reqoff);
 239         struct crypto_ahash *auth = ctx->auth;
 240         u8 *ohash = PTR_ALIGN((u8 *)areq_ctx->tail,
 241                               crypto_ahash_alignmask(auth) + 1);
 242         unsigned int cryptlen = req->cryptlen - authsize;
 243         unsigned int assoclen = req->assoclen;
 244         struct scatterlist *dst = req->dst;
 245         u8 *ihash = ohash + crypto_ahash_digestsize(auth);
 246         u32 tmp[2];
 247
 248         if (!authsize)
 249                 goto decrypt;
 250
 251         /* Move high-order bits of sequence number back. */
 252         scatterwalk_map_and_copy(tmp, dst, 4, 4, 0);
 253         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 0);
 254         scatterwalk_map_and_copy(tmp, dst, 0, 8, 1);
 255
 256         if (crypto_memneq(ihash, ohash, authsize))
 257                 return -EBADMSG;
 258
 259 decrypt:
 260
 261         sg_init_table(areq_ctx->dst, 2);
 262         dst = scatterwalk_ffwd(areq_ctx->dst, dst, assoclen);
 263
 264         ablkcipher_request_set_tfm(abreq, ctx->enc);
 265         ablkcipher_request_set_callback(abreq, flags,
 266                                         req->base.complete, req->base.data);
 267         ablkcipher_request_set_crypt(abreq, dst, dst, cryptlen, req->iv);
 268
 269         return crypto_ablkcipher_decrypt(abreq);
 270 }
 271
 272 static void authenc_esn_verify_ahash_done(struct crypto_async_request *areq,
 273                                           int err)
 274 {
 275         struct aead_request *req = areq->data;
 276
 277         err = err ?: crypto_authenc_esn_decrypt_tail(req, 0);
 278         aead_request_complete(req, err);
 279 }
 280
 281 static int crypto_authenc_esn_decrypt(struct aead_request *req)
 282 {
 283         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 284         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 285         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 286         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
 287         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 288         struct crypto_ahash *auth = ctx->auth;
 289         u8 *ohash = PTR_ALIGN((u8 *)areq_ctx->tail,
 290                               crypto_ahash_alignmask(auth) + 1);
 291         unsigned int assoclen = req->assoclen;
 292         unsigned int cryptlen = req->cryptlen;
 293         u8 *ihash = ohash + crypto_ahash_digestsize(auth);
 294         struct scatterlist *dst = req->dst;
 295         u32 tmp[2];
 296         int err;
 297
 298         cryptlen -= authsize;
 299
 300         if (req->src != dst) {
 301                 err = crypto_authenc_esn_copy(req, assoclen + cryptlen);
 302                 if (err)
 303                         return err;
 304         }
 305
 306         scatterwalk_map_and_copy(ihash, req->src, assoclen + cryptlen,
 307                                  authsize, 0);
 308
 309         if (!authsize)
 310                 goto tail;
 311
 312         /* Move high-order bits of sequence number to the end. */
 313         scatterwalk_map_and_copy(tmp, dst, 0, 8, 0);
 314         scatterwalk_map_and_copy(tmp, dst, 4, 4, 1);
 315         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 1);
 316
 317         sg_init_table(areq_ctx->dst, 2);
 318         dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
 319
 320         ahash_request_set_tfm(ahreq, auth);
 321         ahash_request_set_crypt(ahreq, dst, ohash, assoclen + cryptlen);
 322         ahash_request_set_callback(ahreq, aead_request_flags(req),
 323                                    authenc_esn_verify_ahash_done, req);
 324
 325         err = crypto_ahash_digest(ahreq);
 326         if (err)
 327                 return err;
 328
 329 tail:
 330         return crypto_authenc_esn_decrypt_tail(req, aead_request_flags(req));
 331 }
 332
 333 static int crypto_authenc_esn_init_tfm(struct crypto_aead *tfm)
 334 {
 335         struct aead_instance *inst = aead_alg_instance(tfm);
 336         struct authenc_esn_instance_ctx *ictx = aead_instance_ctx(inst);
 337         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(tfm);
 338         struct crypto_ahash *auth;
 339         struct crypto_ablkcipher *enc;
 340         struct crypto_blkcipher *null;
 341         int err;
 342
 343         auth = crypto_spawn_ahash(&ictx->auth);
 344         if (IS_ERR(auth))
 345                 return PTR_ERR(auth);
 346
 347         enc = crypto_spawn_skcipher(&ictx->enc);
 348         err = PTR_ERR(enc);
 349         if (IS_ERR(enc))
 350                 goto err_free_ahash;
 351
 352         null = crypto_get_default_null_skcipher();
 353         err = PTR_ERR(null);
 354         if (IS_ERR(null))
 355                 goto err_free_skcipher;
 356
 357         ctx->auth = auth;
 358         ctx->enc = enc;
 359         ctx->null = null;
 360
 361         ctx->reqoff = ALIGN(2 * crypto_ahash_digestsize(auth),
 362                             crypto_ahash_alignmask(auth) + 1);
 363
 364         crypto_aead_set_reqsize(
 365                 tfm,
 366                 sizeof(struct authenc_esn_request_ctx) +
 367                 ctx->reqoff +
 368                 max_t(unsigned int,
 369                         crypto_ahash_reqsize(auth) +
 370                         sizeof(struct ahash_request),
 371                         sizeof(struct skcipher_givcrypt_request) +
 372                         crypto_ablkcipher_reqsize(enc)));
 373
 374         return 0;
 375
 376 err_free_skcipher:
 377         crypto_free_ablkcipher(enc);
 378 err_free_ahash:
 379         crypto_free_ahash(auth);
 380         return err;
 381 }
 382
 383 static void crypto_authenc_esn_exit_tfm(struct crypto_aead *tfm)
 384 {
 385         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(tfm);
 386
 387         crypto_free_ahash(ctx->auth);
 388         crypto_free_ablkcipher(ctx->enc);
 389         crypto_put_default_null_skcipher();
 390 }
 391
 392 static void crypto_authenc_esn_free(struct aead_instance *inst)
 393 {
 394         struct authenc_esn_instance_ctx *ctx = aead_instance_ctx(inst);
 395
 396         crypto_drop_skcipher(&ctx->enc);
 397         crypto_drop_ahash(&ctx->auth);
 398         kfree(inst);
 399 }
 400
 401 static int crypto_authenc_esn_create(struct crypto_template *tmpl,
 402                                      struct rtattr **tb)
 403 {
 404         struct crypto_attr_type *algt;
 405         struct aead_instance *inst;
 406         struct hash_alg_common *auth;
 407         struct crypto_alg *auth_base;
 408         struct crypto_alg *enc;
 409         struct authenc_esn_instance_ctx *ctx;
 410         const char *enc_name;
 411         int err;
 412
 413         algt = crypto_get_attr_type(tb);
 414         if (IS_ERR(algt))
 415                 return PTR_ERR(algt);
 416
 417         if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
 418                 return -EINVAL;
 419
 420         auth = ahash_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
 421                                CRYPTO_ALG_TYPE_AHASH_MASK);
 422         if (IS_ERR(auth))
 423                 return PTR_ERR(auth);
 424
 425         auth_base = &auth->base;
 426
 427         enc_name = crypto_attr_alg_name(tb[2]);
 428         err = PTR_ERR(enc_name);
 429         if (IS_ERR(enc_name))
 430                 goto out_put_auth;
 431
 432         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 433         err = -ENOMEM;
 434         if (!inst)
 435                 goto out_put_auth;
 436
 437         ctx = aead_instance_ctx(inst);
 438
 439         err = crypto_init_ahash_spawn(&ctx->auth, auth,
 440                                       aead_crypto_instance(inst));
 441         if (err)
 442                 goto err_free_inst;
 443
 444         crypto_set_skcipher_spawn(&ctx->enc, aead_crypto_instance(inst));
 445         err = crypto_grab_skcipher(&ctx->enc, enc_name, 0,
 446                                    crypto_requires_sync(algt->type,
 447                                                         algt->mask));
 448         if (err)
 449                 goto err_drop_auth;
 450
 451         enc = crypto_skcipher_spawn_alg(&ctx->enc);
 452
 453         err = -ENAMETOOLONG;
 454         if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 455                      "authencesn(%s,%s)", auth_base->cra_name,
 456                      enc->cra_name) >= CRYPTO_MAX_ALG_NAME)
 457                 goto err_drop_enc;
 458
 459         if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 460                      "authencesn(%s,%s)", auth_base->cra_driver_name,
 461                      enc->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 462                 goto err_drop_enc;
 463
 464         inst->alg.base.cra_flags = enc->cra_flags & CRYPTO_ALG_ASYNC;
 465         inst->alg.base.cra_priority = enc->cra_priority * 10 +
 466                                       auth_base->cra_priority;
 467         inst->alg.base.cra_blocksize = enc->cra_blocksize;
 468         inst->alg.base.cra_alignmask = auth_base->cra_alignmask |
 469                                        enc->cra_alignmask;
 470         inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_esn_ctx);
 471
 472         inst->alg.ivsize = enc->cra_ablkcipher.ivsize;
 473         inst->alg.maxauthsize = auth->digestsize;
 474
 475         inst->alg.init = crypto_authenc_esn_init_tfm;
 476         inst->alg.exit = crypto_authenc_esn_exit_tfm;
 477
 478         inst->alg.setkey = crypto_authenc_esn_setkey;
 479         inst->alg.setauthsize = crypto_authenc_esn_setauthsize;
 480         inst->alg.encrypt = crypto_authenc_esn_encrypt;
 481         inst->alg.decrypt = crypto_authenc_esn_decrypt;
 482
 483         inst->free = crypto_authenc_esn_free,
 484
 485         err = aead_register_instance(tmpl, inst);
 486         if (err)
 487                 goto err_drop_enc;
 488
 489 out:
 490         crypto_mod_put(auth_base);
 491         return err;
 492
 493 err_drop_enc:
 494         crypto_drop_skcipher(&ctx->enc);
 495 err_drop_auth:
 496         crypto_drop_ahash(&ctx->auth);
 497 err_free_inst:
 498         kfree(inst);
 499 out_put_auth:
 500         goto out;
 501 }
 502
 503 static struct crypto_template crypto_authenc_esn_tmpl = {
 504         .name = "authencesn",
 505         .create = crypto_authenc_esn_create,
 506         .module = THIS_MODULE,
 507 };
 508
 509 static int __init crypto_authenc_esn_module_init(void)
 510 {
 511         return crypto_register_template(&crypto_authenc_esn_tmpl);
 512 }
 513
 514 static void __exit crypto_authenc_esn_module_exit(void)
 515 {
 516         crypto_unregister_template(&crypto_authenc_esn_tmpl);
 517 }
 518
 519 module_init(crypto_authenc_esn_module_init);
 520 module_exit(crypto_authenc_esn_module_exit);
 521
 522 MODULE_LICENSE("GPL");
 523 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
 524 MODULE_DESCRIPTION("AEAD wrapper for IPsec with extended sequence numbers");
 525 MODULE_ALIAS_CRYPTO("authencesn");