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         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         SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);
 186
 187         skcipher_request_set_tfm(skreq, ctx->null);
 188         skcipher_request_set_callback(skreq, aead_request_flags(req),
 189                                       NULL, NULL);
 190         skcipher_request_set_crypt(skreq, req->src, req->dst, len, NULL);
 191
 192         return crypto_skcipher_encrypt(skreq);
 193 }
 194
 195 static int crypto_authenc_esn_encrypt(struct aead_request *req)
 196 {
 197         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 198         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 199         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 200         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 201                                                   ctx->reqoff);
 202         struct crypto_skcipher *enc = ctx->enc;
 203         unsigned int assoclen = req->assoclen;
 204         unsigned int cryptlen = req->cryptlen;
 205         struct scatterlist *src, *dst;
 206         int err;
 207
 208         sg_init_table(areq_ctx->src, 2);
 209         src = scatterwalk_ffwd(areq_ctx->src, req->src, assoclen);
 210         dst = src;
 211
 212         if (req->src != req->dst) {
 213                 err = crypto_authenc_esn_copy(req, assoclen);
 214                 if (err)
 215                         return err;
 216
 217                 sg_init_table(areq_ctx->dst, 2);
 218                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, assoclen);
 219         }
 220
 221         skcipher_request_set_tfm(skreq, enc);
 222         skcipher_request_set_callback(skreq, aead_request_flags(req),
 223                                       crypto_authenc_esn_encrypt_done, req);
 224         skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
 225
 226         err = crypto_skcipher_encrypt(skreq);
 227         if (err)
 228                 return err;
 229
 230         return crypto_authenc_esn_genicv(req, aead_request_flags(req));
 231 }
 232
 233 static int crypto_authenc_esn_decrypt_tail(struct aead_request *req,
 234                                            unsigned int flags)
 235 {
 236         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 237         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 238         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 239         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 240         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 241                                                   ctx->reqoff);
 242         struct crypto_ahash *auth = ctx->auth;
 243         u8 *ohash = PTR_ALIGN((u8 *)areq_ctx->tail,
 244                               crypto_ahash_alignmask(auth) + 1);
 245         unsigned int cryptlen = req->cryptlen - authsize;
 246         unsigned int assoclen = req->assoclen;
 247         struct scatterlist *dst = req->dst;
 248         u8 *ihash = ohash + crypto_ahash_digestsize(auth);
 249         u32 tmp[2];
 250
 251         if (!authsize)
 252                 goto decrypt;
 253
 254         /* Move high-order bits of sequence number back. */
 255         scatterwalk_map_and_copy(tmp, dst, 4, 4, 0);
 256         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 0);
 257         scatterwalk_map_and_copy(tmp, dst, 0, 8, 1);
 258
 259         if (crypto_memneq(ihash, ohash, authsize))
 260                 return -EBADMSG;
 261
 262 decrypt:
 263
 264         sg_init_table(areq_ctx->dst, 2);
 265         dst = scatterwalk_ffwd(areq_ctx->dst, dst, assoclen);
 266
 267         skcipher_request_set_tfm(skreq, ctx->enc);
 268         skcipher_request_set_callback(skreq, flags,
 269                                       req->base.complete, req->base.data);
 270         skcipher_request_set_crypt(skreq, dst, dst, cryptlen, req->iv);
 271
 272         return crypto_skcipher_decrypt(skreq);
 273 }
 274
 275 static void authenc_esn_verify_ahash_done(struct crypto_async_request *areq,
 276                                           int err)
 277 {
 278         struct aead_request *req = areq->data;
 279
 280         err = err ?: crypto_authenc_esn_decrypt_tail(req, 0);
 281         aead_request_complete(req, err);
 282 }
 283
 284 static int crypto_authenc_esn_decrypt(struct aead_request *req)
 285 {
 286         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 287         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 288         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 289         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
 290         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 291         struct crypto_ahash *auth = ctx->auth;
 292         u8 *ohash = PTR_ALIGN((u8 *)areq_ctx->tail,
 293                               crypto_ahash_alignmask(auth) + 1);
 294         unsigned int assoclen = req->assoclen;
 295         unsigned int cryptlen = req->cryptlen;
 296         u8 *ihash = ohash + crypto_ahash_digestsize(auth);
 297         struct scatterlist *dst = req->dst;
 298         u32 tmp[2];
 299         int err;
 300
 301         cryptlen -= authsize;
 302
 303         if (req->src != dst) {
 304                 err = crypto_authenc_esn_copy(req, assoclen + cryptlen);
 305                 if (err)
 306                         return err;
 307         }
 308
 309         scatterwalk_map_and_copy(ihash, req->src, assoclen + cryptlen,
 310                                  authsize, 0);
 311
 312         if (!authsize)
 313                 goto tail;
 314
 315         /* Move high-order bits of sequence number to the end. */
 316         scatterwalk_map_and_copy(tmp, dst, 0, 8, 0);
 317         scatterwalk_map_and_copy(tmp, dst, 4, 4, 1);
 318         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 1);
 319
 320         sg_init_table(areq_ctx->dst, 2);
 321         dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
 322
 323         ahash_request_set_tfm(ahreq, auth);
 324         ahash_request_set_crypt(ahreq, dst, ohash, assoclen + cryptlen);
 325         ahash_request_set_callback(ahreq, aead_request_flags(req),
 326                                    authenc_esn_verify_ahash_done, req);
 327
 328         err = crypto_ahash_digest(ahreq);
 329         if (err)
 330                 return err;
 331
 332 tail:
 333         return crypto_authenc_esn_decrypt_tail(req, aead_request_flags(req));
 334 }
 335
 336 static int crypto_authenc_esn_init_tfm(struct crypto_aead *tfm)
 337 {
 338         struct aead_instance *inst = aead_alg_instance(tfm);
 339         struct authenc_esn_instance_ctx *ictx = aead_instance_ctx(inst);
 340         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(tfm);
 341         struct crypto_ahash *auth;
 342         struct crypto_skcipher *enc;
 343         struct crypto_skcipher *null;
 344         int err;
 345
 346         auth = crypto_spawn_ahash(&ictx->auth);
 347         if (IS_ERR(auth))
 348                 return PTR_ERR(auth);
 349
 350         enc = crypto_spawn_skcipher(&ictx->enc);
 351         err = PTR_ERR(enc);
 352         if (IS_ERR(enc))
 353                 goto err_free_ahash;
 354
 355         null = crypto_get_default_null_skcipher();
 356         err = PTR_ERR(null);
 357         if (IS_ERR(null))
 358                 goto err_free_skcipher;
 359
 360         ctx->auth = auth;
 361         ctx->enc = enc;
 362         ctx->null = null;
 363
 364         ctx->reqoff = ALIGN(2 * crypto_ahash_digestsize(auth),
 365                             crypto_ahash_alignmask(auth) + 1);
 366
 367         crypto_aead_set_reqsize(
 368                 tfm,
 369                 sizeof(struct authenc_esn_request_ctx) +
 370                 ctx->reqoff +
 371                 max_t(unsigned int,
 372                       crypto_ahash_reqsize(auth) +
 373                       sizeof(struct ahash_request),
 374                       sizeof(struct skcipher_request) +
 375                       crypto_skcipher_reqsize(enc)));
 376
 377         return 0;
 378
 379 err_free_skcipher:
 380         crypto_free_skcipher(enc);
 381 err_free_ahash:
 382         crypto_free_ahash(auth);
 383         return err;
 384 }
 385
 386 static void crypto_authenc_esn_exit_tfm(struct crypto_aead *tfm)
 387 {
 388         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(tfm);
 389
 390         crypto_free_ahash(ctx->auth);
 391         crypto_free_skcipher(ctx->enc);
 392         crypto_put_default_null_skcipher();
 393 }
 394
 395 static void crypto_authenc_esn_free(struct aead_instance *inst)
 396 {
 397         struct authenc_esn_instance_ctx *ctx = aead_instance_ctx(inst);
 398
 399         crypto_drop_skcipher(&ctx->enc);
 400         crypto_drop_ahash(&ctx->auth);
 401         kfree(inst);
 402 }
 403
 404 static int crypto_authenc_esn_create(struct crypto_template *tmpl,
 405                                      struct rtattr **tb)
 406 {
 407         struct crypto_attr_type *algt;
 408         struct aead_instance *inst;
 409         struct hash_alg_common *auth;
 410         struct crypto_alg *auth_base;
 411         struct skcipher_alg *enc;
 412         struct authenc_esn_instance_ctx *ctx;
 413         const char *enc_name;
 414         int err;
 415
 416         algt = crypto_get_attr_type(tb);
 417         if (IS_ERR(algt))
 418                 return PTR_ERR(algt);
 419
 420         if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
 421                 return -EINVAL;
 422
 423         auth = ahash_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
 424                               CRYPTO_ALG_TYPE_AHASH_MASK |
 425                               crypto_requires_sync(algt->type, algt->mask));
 426         if (IS_ERR(auth))
 427                 return PTR_ERR(auth);
 428
 429         auth_base = &auth->base;
 430
 431         enc_name = crypto_attr_alg_name(tb[2]);
 432         err = PTR_ERR(enc_name);
 433         if (IS_ERR(enc_name))
 434                 goto out_put_auth;
 435
 436         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 437         err = -ENOMEM;
 438         if (!inst)
 439                 goto out_put_auth;
 440
 441         ctx = aead_instance_ctx(inst);
 442
 443         err = crypto_init_ahash_spawn(&ctx->auth, auth,
 444                                       aead_crypto_instance(inst));
 445         if (err)
 446                 goto err_free_inst;
 447
 448         crypto_set_skcipher_spawn(&ctx->enc, aead_crypto_instance(inst));
 449         err = crypto_grab_skcipher(&ctx->enc, enc_name, 0,
 450                                    crypto_requires_sync(algt->type,
 451                                                         algt->mask));
 452         if (err)
 453                 goto err_drop_auth;
 454
 455         enc = crypto_spawn_skcipher_alg(&ctx->enc);
 456
 457         err = -ENAMETOOLONG;
 458         if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 459                      "authencesn(%s,%s)", auth_base->cra_name,
 460                      enc->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
 461                 goto err_drop_enc;
 462
 463         if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 464                      "authencesn(%s,%s)", auth_base->cra_driver_name,
 465                      enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 466                 goto err_drop_enc;
 467
 468         inst->alg.base.cra_flags = (auth_base->cra_flags |
 469                                     enc->base.cra_flags) & CRYPTO_ALG_ASYNC;
 470         inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
 471                                       auth_base->cra_priority;
 472         inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
 473         inst->alg.base.cra_alignmask = auth_base->cra_alignmask |
 474                                        enc->base.cra_alignmask;
 475         inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_esn_ctx);
 476
 477         inst->alg.ivsize = crypto_skcipher_alg_ivsize(enc);
 478         inst->alg.chunksize = crypto_skcipher_alg_chunksize(enc);
 479         inst->alg.maxauthsize = auth->digestsize;
 480
 481         inst->alg.init = crypto_authenc_esn_init_tfm;
 482         inst->alg.exit = crypto_authenc_esn_exit_tfm;
 483
 484         inst->alg.setkey = crypto_authenc_esn_setkey;
 485         inst->alg.setauthsize = crypto_authenc_esn_setauthsize;
 486         inst->alg.encrypt = crypto_authenc_esn_encrypt;
 487         inst->alg.decrypt = crypto_authenc_esn_decrypt;
 488
 489         inst->free = crypto_authenc_esn_free,
 490
 491         err = aead_register_instance(tmpl, inst);
 492         if (err)
 493                 goto err_drop_enc;
 494
 495 out:
 496         crypto_mod_put(auth_base);
 497         return err;
 498
 499 err_drop_enc:
 500         crypto_drop_skcipher(&ctx->enc);
 501 err_drop_auth:
 502         crypto_drop_ahash(&ctx->auth);
 503 err_free_inst:
 504         kfree(inst);
 505 out_put_auth:
 506         goto out;
 507 }
 508
 509 static struct crypto_template crypto_authenc_esn_tmpl = {
 510         .name = "authencesn",
 511         .create = crypto_authenc_esn_create,
 512         .module = THIS_MODULE,
 513 };
 514
 515 static int __init crypto_authenc_esn_module_init(void)
 516 {
 517         return crypto_register_template(&crypto_authenc_esn_tmpl);
 518 }
 519
 520 static void __exit crypto_authenc_esn_module_exit(void)
 521 {
 522         crypto_unregister_template(&crypto_authenc_esn_tmpl);
 523 }
 524
 525 module_init(crypto_authenc_esn_module_init);
 526 module_exit(crypto_authenc_esn_module_exit);
 527
 528 MODULE_LICENSE("GPL");
 529 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
 530 MODULE_DESCRIPTION("AEAD wrapper for IPsec with extended sequence numbers");
 531 MODULE_ALIAS_CRYPTO("authencesn");