crypto/authencesn.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * authencesn.c - AEAD wrapper for IPsec with extended sequence numbers,
   4  *                 derived from authenc.c
   5  *
   6  * Copyright (C) 2010 secunet Security Networks AG
   7  * Copyright (C) 2010 Steffen Klassert <steffen.klassert@secunet.com>
   8  * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
   9  */
  10
  11 #include <crypto/internal/aead.h>
  12 #include <crypto/internal/hash.h>
  13 #include <crypto/internal/skcipher.h>
  14 #include <crypto/authenc.h>
  15 #include <crypto/null.h>
  16 #include <crypto/scatterwalk.h>
  17 #include <linux/err.h>
  18 #include <linux/init.h>
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/rtnetlink.h>
  22 #include <linux/slab.h>
  23 #include <linux/spinlock.h>
  24
  25 struct authenc_esn_instance_ctx {
  26         struct crypto_ahash_spawn auth;
  27         struct crypto_skcipher_spawn enc;
  28 };
  29
  30 struct crypto_authenc_esn_ctx {
  31         unsigned int reqoff;
  32         struct crypto_ahash *auth;
  33         struct crypto_skcipher *enc;
  34         struct crypto_sync_skcipher *null;
  35 };
  36
  37 struct authenc_esn_request_ctx {
  38         struct scatterlist src[2];
  39         struct scatterlist dst[2];
  40         char tail[];
  41 };
  42
  43 static void authenc_esn_request_complete(struct aead_request *req, int err)
  44 {
  45         if (err != -EINPROGRESS)
  46                 aead_request_complete(req, err);
  47 }
  48
  49 static int crypto_authenc_esn_setauthsize(struct crypto_aead *authenc_esn,
  50                                           unsigned int authsize)
  51 {
  52         if (authsize > 0 && authsize < 4)
  53                 return -EINVAL;
  54
  55         return 0;
  56 }
  57
  58 static int crypto_authenc_esn_setkey(struct crypto_aead *authenc_esn, const u8 *key,
  59                                      unsigned int keylen)
  60 {
  61         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
  62         struct crypto_ahash *auth = ctx->auth;
  63         struct crypto_skcipher *enc = ctx->enc;
  64         struct crypto_authenc_keys keys;
  65         int err = -EINVAL;
  66
  67         if (crypto_authenc_extractkeys(&keys, key, keylen) != 0)
  68                 goto out;
  69
  70         crypto_ahash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
  71         crypto_ahash_set_flags(auth, crypto_aead_get_flags(authenc_esn) &
  72                                      CRYPTO_TFM_REQ_MASK);
  73         err = crypto_ahash_setkey(auth, keys.authkey, keys.authkeylen);
  74         if (err)
  75                 goto out;
  76
  77         crypto_skcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
  78         crypto_skcipher_set_flags(enc, crypto_aead_get_flags(authenc_esn) &
  79                                          CRYPTO_TFM_REQ_MASK);
  80         err = crypto_skcipher_setkey(enc, keys.enckey, keys.enckeylen);
  81 out:
  82         memzero_explicit(&keys, sizeof(keys));
  83         return err;
  84 }
  85
  86 static int crypto_authenc_esn_genicv_tail(struct aead_request *req,
  87                                           unsigned int flags)
  88 {
  89         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
  90         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
  91         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
  92         struct crypto_ahash *auth = ctx->auth;
  93         u8 *hash = PTR_ALIGN((u8 *)areq_ctx->tail,
  94                              crypto_ahash_alignmask(auth) + 1);
  95         unsigned int authsize = crypto_aead_authsize(authenc_esn);
  96         unsigned int assoclen = req->assoclen;
  97         unsigned int cryptlen = req->cryptlen;
  98         struct scatterlist *dst = req->dst;
  99         u32 tmp[2];
 100
 101         /* Move high-order bits of sequence number back. */
 102         scatterwalk_map_and_copy(tmp, dst, 4, 4, 0);
 103         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 0);
 104         scatterwalk_map_and_copy(tmp, dst, 0, 8, 1);
 105
 106         scatterwalk_map_and_copy(hash, dst, assoclen + cryptlen, authsize, 1);
 107         return 0;
 108 }
 109
 110 static void authenc_esn_geniv_ahash_done(struct crypto_async_request *areq,
 111                                          int err)
 112 {
 113         struct aead_request *req = areq->data;
 114
 115         err = err ?: crypto_authenc_esn_genicv_tail(req, 0);
 116         aead_request_complete(req, err);
 117 }
 118
 119 static int crypto_authenc_esn_genicv(struct aead_request *req,
 120                                      unsigned int flags)
 121 {
 122         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 123         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 124         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 125         struct crypto_ahash *auth = ctx->auth;
 126         u8 *hash = PTR_ALIGN((u8 *)areq_ctx->tail,
 127                              crypto_ahash_alignmask(auth) + 1);
 128         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
 129         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 130         unsigned int assoclen = req->assoclen;
 131         unsigned int cryptlen = req->cryptlen;
 132         struct scatterlist *dst = req->dst;
 133         u32 tmp[2];
 134
 135         if (!authsize)
 136                 return 0;
 137
 138         /* Move high-order bits of sequence number to the end. */
 139         scatterwalk_map_and_copy(tmp, dst, 0, 8, 0);
 140         scatterwalk_map_and_copy(tmp, dst, 4, 4, 1);
 141         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 1);
 142
 143         sg_init_table(areq_ctx->dst, 2);
 144         dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
 145
 146         ahash_request_set_tfm(ahreq, auth);
 147         ahash_request_set_crypt(ahreq, dst, hash, assoclen + cryptlen);
 148         ahash_request_set_callback(ahreq, flags,
 149                                    authenc_esn_geniv_ahash_done, req);
 150
 151         return crypto_ahash_digest(ahreq) ?:
 152                crypto_authenc_esn_genicv_tail(req, aead_request_flags(req));
 153 }
 154
 155
 156 static void crypto_authenc_esn_encrypt_done(struct crypto_async_request *req,
 157                                             int err)
 158 {
 159         struct aead_request *areq = req->data;
 160
 161         if (!err)
 162                 err = crypto_authenc_esn_genicv(areq, 0);
 163
 164         authenc_esn_request_complete(areq, err);
 165 }
 166
 167 static int crypto_authenc_esn_copy(struct aead_request *req, unsigned int len)
 168 {
 169         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 170         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 171         SYNC_SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);
 172
 173         skcipher_request_set_sync_tfm(skreq, ctx->null);
 174         skcipher_request_set_callback(skreq, aead_request_flags(req),
 175                                       NULL, NULL);
 176         skcipher_request_set_crypt(skreq, req->src, req->dst, len, NULL);
 177
 178         return crypto_skcipher_encrypt(skreq);
 179 }
 180
 181 static int crypto_authenc_esn_encrypt(struct aead_request *req)
 182 {
 183         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 184         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 185         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 186         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 187                                                   ctx->reqoff);
 188         struct crypto_skcipher *enc = ctx->enc;
 189         unsigned int assoclen = req->assoclen;
 190         unsigned int cryptlen = req->cryptlen;
 191         struct scatterlist *src, *dst;
 192         int err;
 193
 194         sg_init_table(areq_ctx->src, 2);
 195         src = scatterwalk_ffwd(areq_ctx->src, req->src, assoclen);
 196         dst = src;
 197
 198         if (req->src != req->dst) {
 199                 err = crypto_authenc_esn_copy(req, assoclen);
 200                 if (err)
 201                         return err;
 202
 203                 sg_init_table(areq_ctx->dst, 2);
 204                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, assoclen);
 205         }
 206
 207         skcipher_request_set_tfm(skreq, enc);
 208         skcipher_request_set_callback(skreq, aead_request_flags(req),
 209                                       crypto_authenc_esn_encrypt_done, req);
 210         skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
 211
 212         err = crypto_skcipher_encrypt(skreq);
 213         if (err)
 214                 return err;
 215
 216         return crypto_authenc_esn_genicv(req, aead_request_flags(req));
 217 }
 218
 219 static int crypto_authenc_esn_decrypt_tail(struct aead_request *req,
 220                                            unsigned int flags)
 221 {
 222         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 223         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 224         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 225         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 226         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 227                                                   ctx->reqoff);
 228         struct crypto_ahash *auth = ctx->auth;
 229         u8 *ohash = PTR_ALIGN((u8 *)areq_ctx->tail,
 230                               crypto_ahash_alignmask(auth) + 1);
 231         unsigned int cryptlen = req->cryptlen - authsize;
 232         unsigned int assoclen = req->assoclen;
 233         struct scatterlist *dst = req->dst;
 234         u8 *ihash = ohash + crypto_ahash_digestsize(auth);
 235         u32 tmp[2];
 236
 237         if (!authsize)
 238                 goto decrypt;
 239
 240         /* Move high-order bits of sequence number back. */
 241         scatterwalk_map_and_copy(tmp, dst, 4, 4, 0);
 242         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 0);
 243         scatterwalk_map_and_copy(tmp, dst, 0, 8, 1);
 244
 245         if (crypto_memneq(ihash, ohash, authsize))
 246                 return -EBADMSG;
 247
 248 decrypt:
 249
 250         sg_init_table(areq_ctx->dst, 2);
 251         dst = scatterwalk_ffwd(areq_ctx->dst, dst, assoclen);
 252
 253         skcipher_request_set_tfm(skreq, ctx->enc);
 254         skcipher_request_set_callback(skreq, flags,
 255                                       req->base.complete, req->base.data);
 256         skcipher_request_set_crypt(skreq, dst, dst, cryptlen, req->iv);
 257
 258         return crypto_skcipher_decrypt(skreq);
 259 }
 260
 261 static void authenc_esn_verify_ahash_done(struct crypto_async_request *areq,
 262                                           int err)
 263 {
 264         struct aead_request *req = areq->data;
 265
 266         err = err ?: crypto_authenc_esn_decrypt_tail(req, 0);
 267         authenc_esn_request_complete(req, err);
 268 }
 269
 270 static int crypto_authenc_esn_decrypt(struct aead_request *req)
 271 {
 272         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 273         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 274         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 275         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
 276         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 277         struct crypto_ahash *auth = ctx->auth;
 278         u8 *ohash = PTR_ALIGN((u8 *)areq_ctx->tail,
 279                               crypto_ahash_alignmask(auth) + 1);
 280         unsigned int assoclen = req->assoclen;
 281         unsigned int cryptlen = req->cryptlen;
 282         u8 *ihash = ohash + crypto_ahash_digestsize(auth);
 283         struct scatterlist *dst = req->dst;
 284         u32 tmp[2];
 285         int err;
 286
 287         cryptlen -= authsize;
 288
 289         if (req->src != dst) {
 290                 err = crypto_authenc_esn_copy(req, assoclen + cryptlen);
 291                 if (err)
 292                         return err;
 293         }
 294
 295         scatterwalk_map_and_copy(ihash, req->src, assoclen + cryptlen,
 296                                  authsize, 0);
 297
 298         if (!authsize)
 299                 goto tail;
 300
 301         /* Move high-order bits of sequence number to the end. */
 302         scatterwalk_map_and_copy(tmp, dst, 0, 8, 0);
 303         scatterwalk_map_and_copy(tmp, dst, 4, 4, 1);
 304         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 1);
 305
 306         sg_init_table(areq_ctx->dst, 2);
 307         dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
 308
 309         ahash_request_set_tfm(ahreq, auth);
 310         ahash_request_set_crypt(ahreq, dst, ohash, assoclen + cryptlen);
 311         ahash_request_set_callback(ahreq, aead_request_flags(req),
 312                                    authenc_esn_verify_ahash_done, req);
 313
 314         err = crypto_ahash_digest(ahreq);
 315         if (err)
 316                 return err;
 317
 318 tail:
 319         return crypto_authenc_esn_decrypt_tail(req, aead_request_flags(req));
 320 }
 321
 322 static int crypto_authenc_esn_init_tfm(struct crypto_aead *tfm)
 323 {
 324         struct aead_instance *inst = aead_alg_instance(tfm);
 325         struct authenc_esn_instance_ctx *ictx = aead_instance_ctx(inst);
 326         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(tfm);
 327         struct crypto_ahash *auth;
 328         struct crypto_skcipher *enc;
 329         struct crypto_sync_skcipher *null;
 330         int err;
 331
 332         auth = crypto_spawn_ahash(&ictx->auth);
 333         if (IS_ERR(auth))
 334                 return PTR_ERR(auth);
 335
 336         enc = crypto_spawn_skcipher(&ictx->enc);
 337         err = PTR_ERR(enc);
 338         if (IS_ERR(enc))
 339                 goto err_free_ahash;
 340
 341         null = crypto_get_default_null_skcipher();
 342         err = PTR_ERR(null);
 343         if (IS_ERR(null))
 344                 goto err_free_skcipher;
 345
 346         ctx->auth = auth;
 347         ctx->enc = enc;
 348         ctx->null = null;
 349
 350         ctx->reqoff = ALIGN(2 * crypto_ahash_digestsize(auth),
 351                             crypto_ahash_alignmask(auth) + 1);
 352
 353         crypto_aead_set_reqsize(
 354                 tfm,
 355                 sizeof(struct authenc_esn_request_ctx) +
 356                 ctx->reqoff +
 357                 max_t(unsigned int,
 358                       crypto_ahash_reqsize(auth) +
 359                       sizeof(struct ahash_request),
 360                       sizeof(struct skcipher_request) +
 361                       crypto_skcipher_reqsize(enc)));
 362
 363         return 0;
 364
 365 err_free_skcipher:
 366         crypto_free_skcipher(enc);
 367 err_free_ahash:
 368         crypto_free_ahash(auth);
 369         return err;
 370 }
 371
 372 static void crypto_authenc_esn_exit_tfm(struct crypto_aead *tfm)
 373 {
 374         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(tfm);
 375
 376         crypto_free_ahash(ctx->auth);
 377         crypto_free_skcipher(ctx->enc);
 378         crypto_put_default_null_skcipher();
 379 }
 380
 381 static void crypto_authenc_esn_free(struct aead_instance *inst)
 382 {
 383         struct authenc_esn_instance_ctx *ctx = aead_instance_ctx(inst);
 384
 385         crypto_drop_skcipher(&ctx->enc);
 386         crypto_drop_ahash(&ctx->auth);
 387         kfree(inst);
 388 }
 389
 390 static int crypto_authenc_esn_create(struct crypto_template *tmpl,
 391                                      struct rtattr **tb)
 392 {
 393         u32 mask;
 394         struct aead_instance *inst;
 395         struct authenc_esn_instance_ctx *ctx;
 396         struct hash_alg_common *auth;
 397         struct crypto_alg *auth_base;
 398         struct skcipher_alg *enc;
 399         int err;
 400
 401         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD, &mask);
 402         if (err)
 403                 return err;
 404
 405         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 406         if (!inst)
 407                 return -ENOMEM;
 408         ctx = aead_instance_ctx(inst);
 409
 410         err = crypto_grab_ahash(&ctx->auth, aead_crypto_instance(inst),
 411                                 crypto_attr_alg_name(tb[1]), 0, mask);
 412         if (err)
 413                 goto err_free_inst;
 414         auth = crypto_spawn_ahash_alg(&ctx->auth);
 415         auth_base = &auth->base;
 416
 417         err = crypto_grab_skcipher(&ctx->enc, aead_crypto_instance(inst),
 418                                    crypto_attr_alg_name(tb[2]), 0, mask);
 419         if (err)
 420                 goto err_free_inst;
 421         enc = crypto_spawn_skcipher_alg(&ctx->enc);
 422
 423         err = -ENAMETOOLONG;
 424         if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 425                      "authencesn(%s,%s)", auth_base->cra_name,
 426                      enc->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
 427                 goto err_free_inst;
 428
 429         if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 430                      "authencesn(%s,%s)", auth_base->cra_driver_name,
 431                      enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 432                 goto err_free_inst;
 433
 434         inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
 435                                       auth_base->cra_priority;
 436         inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
 437         inst->alg.base.cra_alignmask = auth_base->cra_alignmask |
 438                                        enc->base.cra_alignmask;
 439         inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_esn_ctx);
 440
 441         inst->alg.ivsize = crypto_skcipher_alg_ivsize(enc);
 442         inst->alg.chunksize = crypto_skcipher_alg_chunksize(enc);
 443         inst->alg.maxauthsize = auth->digestsize;
 444
 445         inst->alg.init = crypto_authenc_esn_init_tfm;
 446         inst->alg.exit = crypto_authenc_esn_exit_tfm;
 447
 448         inst->alg.setkey = crypto_authenc_esn_setkey;
 449         inst->alg.setauthsize = crypto_authenc_esn_setauthsize;
 450         inst->alg.encrypt = crypto_authenc_esn_encrypt;
 451         inst->alg.decrypt = crypto_authenc_esn_decrypt;
 452
 453         inst->free = crypto_authenc_esn_free;
 454
 455         err = aead_register_instance(tmpl, inst);
 456         if (err) {
 457 err_free_inst:
 458                 crypto_authenc_esn_free(inst);
 459         }
 460         return err;
 461 }
 462
 463 static struct crypto_template crypto_authenc_esn_tmpl = {
 464         .name = "authencesn",
 465         .create = crypto_authenc_esn_create,
 466         .module = THIS_MODULE,
 467 };
 468
 469 static int __init crypto_authenc_esn_module_init(void)
 470 {
 471         return crypto_register_template(&crypto_authenc_esn_tmpl);
 472 }
 473
 474 static void __exit crypto_authenc_esn_module_exit(void)
 475 {
 476         crypto_unregister_template(&crypto_authenc_esn_tmpl);
 477 }
 478
 479 subsys_initcall(crypto_authenc_esn_module_init);
 480 module_exit(crypto_authenc_esn_module_exit);
 481
 482 MODULE_LICENSE("GPL");
 483 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
 484 MODULE_DESCRIPTION("AEAD wrapper for IPsec with extended sequence numbers");
 485 MODULE_ALIAS_CRYPTO("authencesn");