crypto/authenc.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Authenc: Simple AEAD wrapper for IPsec
   4  *
   5  * Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au>
   6  */
   7
   8 #include <crypto/internal/aead.h>
   9 #include <crypto/internal/hash.h>
  10 #include <crypto/internal/skcipher.h>
  11 #include <crypto/authenc.h>
  12 #include <crypto/null.h>
  13 #include <crypto/scatterwalk.h>
  14 #include <linux/err.h>
  15 #include <linux/init.h>
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/rtnetlink.h>
  19 #include <linux/slab.h>
  20 #include <linux/spinlock.h>
  21
  22 struct authenc_instance_ctx {
  23         struct crypto_ahash_spawn auth;
  24         struct crypto_skcipher_spawn enc;
  25         unsigned int reqoff;
  26 };
  27
  28 struct crypto_authenc_ctx {
  29         struct crypto_ahash *auth;
  30         struct crypto_skcipher *enc;
  31         struct crypto_sync_skcipher *null;
  32 };
  33
  34 struct authenc_request_ctx {
  35         struct scatterlist src[2];
  36         struct scatterlist dst[2];
  37         char tail[];
  38 };
  39
  40 static void authenc_request_complete(struct aead_request *req, int err)
  41 {
  42         if (err != -EINPROGRESS)
  43                 aead_request_complete(req, err);
  44 }
  45
  46 int crypto_authenc_extractkeys(struct crypto_authenc_keys *keys, const u8 *key,
  47                                unsigned int keylen)
  48 {
  49         struct rtattr *rta = (struct rtattr *)key;
  50         struct crypto_authenc_key_param *param;
  51
  52         if (!RTA_OK(rta, keylen))
  53                 return -EINVAL;
  54         if (rta->rta_type != CRYPTO_AUTHENC_KEYA_PARAM)
  55                 return -EINVAL;
  56
  57         /*
  58          * RTA_OK() didn't align the rtattr's payload when validating that it
  59          * fits in the buffer.  Yet, the keys should start on the next 4-byte
  60          * aligned boundary.  To avoid confusion, require that the rtattr
  61          * payload be exactly the param struct, which has a 4-byte aligned size.
  62          */
  63         if (RTA_PAYLOAD(rta) != sizeof(*param))
  64                 return -EINVAL;
  65         BUILD_BUG_ON(sizeof(*param) % RTA_ALIGNTO);
  66
  67         param = RTA_DATA(rta);
  68         keys->enckeylen = be32_to_cpu(param->enckeylen);
  69
  70         key += rta->rta_len;
  71         keylen -= rta->rta_len;
  72
  73         if (keylen < keys->enckeylen)
  74                 return -EINVAL;
  75
  76         keys->authkeylen = keylen - keys->enckeylen;
  77         keys->authkey = key;
  78         keys->enckey = key + keys->authkeylen;
  79
  80         return 0;
  81 }
  82 EXPORT_SYMBOL_GPL(crypto_authenc_extractkeys);
  83
  84 static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
  85                                  unsigned int keylen)
  86 {
  87         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  88         struct crypto_ahash *auth = ctx->auth;
  89         struct crypto_skcipher *enc = ctx->enc;
  90         struct crypto_authenc_keys keys;
  91         int err = -EINVAL;
  92
  93         if (crypto_authenc_extractkeys(&keys, key, keylen) != 0)
  94                 goto badkey;
  95
  96         crypto_ahash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
  97         crypto_ahash_set_flags(auth, crypto_aead_get_flags(authenc) &
  98                                     CRYPTO_TFM_REQ_MASK);
  99         err = crypto_ahash_setkey(auth, keys.authkey, keys.authkeylen);
 100         crypto_aead_set_flags(authenc, crypto_ahash_get_flags(auth) &
 101                                        CRYPTO_TFM_RES_MASK);
 102
 103         if (err)
 104                 goto out;
 105
 106         crypto_skcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
 107         crypto_skcipher_set_flags(enc, crypto_aead_get_flags(authenc) &
 108                                        CRYPTO_TFM_REQ_MASK);
 109         err = crypto_skcipher_setkey(enc, keys.enckey, keys.enckeylen);
 110         crypto_aead_set_flags(authenc, crypto_skcipher_get_flags(enc) &
 111                                        CRYPTO_TFM_RES_MASK);
 112
 113 out:
 114         memzero_explicit(&keys, sizeof(keys));
 115         return err;
 116
 117 badkey:
 118         crypto_aead_set_flags(authenc, CRYPTO_TFM_RES_BAD_KEY_LEN);
 119         goto out;
 120 }
 121
 122 static void authenc_geniv_ahash_done(struct crypto_async_request *areq, int err)
 123 {
 124         struct aead_request *req = areq->data;
 125         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 126         struct aead_instance *inst = aead_alg_instance(authenc);
 127         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 128         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 129         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 130
 131         if (err)
 132                 goto out;
 133
 134         scatterwalk_map_and_copy(ahreq->result, req->dst,
 135                                  req->assoclen + req->cryptlen,
 136                                  crypto_aead_authsize(authenc), 1);
 137
 138 out:
 139         aead_request_complete(req, err);
 140 }
 141
 142 static int crypto_authenc_genicv(struct aead_request *req, unsigned int flags)
 143 {
 144         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 145         struct aead_instance *inst = aead_alg_instance(authenc);
 146         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 147         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 148         struct crypto_ahash *auth = ctx->auth;
 149         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 150         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 151         u8 *hash = areq_ctx->tail;
 152         int err;
 153
 154         hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
 155                            crypto_ahash_alignmask(auth) + 1);
 156
 157         ahash_request_set_tfm(ahreq, auth);
 158         ahash_request_set_crypt(ahreq, req->dst, hash,
 159                                 req->assoclen + req->cryptlen);
 160         ahash_request_set_callback(ahreq, flags,
 161                                    authenc_geniv_ahash_done, req);
 162
 163         err = crypto_ahash_digest(ahreq);
 164         if (err)
 165                 return err;
 166
 167         scatterwalk_map_and_copy(hash, req->dst, req->assoclen + req->cryptlen,
 168                                  crypto_aead_authsize(authenc), 1);
 169
 170         return 0;
 171 }
 172
 173 static void crypto_authenc_encrypt_done(struct crypto_async_request *req,
 174                                         int err)
 175 {
 176         struct aead_request *areq = req->data;
 177
 178         if (err)
 179                 goto out;
 180
 181         err = crypto_authenc_genicv(areq, 0);
 182
 183 out:
 184         authenc_request_complete(areq, err);
 185 }
 186
 187 static int crypto_authenc_copy_assoc(struct aead_request *req)
 188 {
 189         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 190         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 191         SYNC_SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);
 192
 193         skcipher_request_set_sync_tfm(skreq, ctx->null);
 194         skcipher_request_set_callback(skreq, aead_request_flags(req),
 195                                       NULL, NULL);
 196         skcipher_request_set_crypt(skreq, req->src, req->dst, req->assoclen,
 197                                    NULL);
 198
 199         return crypto_skcipher_encrypt(skreq);
 200 }
 201
 202 static int crypto_authenc_encrypt(struct aead_request *req)
 203 {
 204         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 205         struct aead_instance *inst = aead_alg_instance(authenc);
 206         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 207         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 208         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 209         struct crypto_skcipher *enc = ctx->enc;
 210         unsigned int cryptlen = req->cryptlen;
 211         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 212                                                   ictx->reqoff);
 213         struct scatterlist *src, *dst;
 214         int err;
 215
 216         src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
 217         dst = src;
 218
 219         if (req->src != req->dst) {
 220                 err = crypto_authenc_copy_assoc(req);
 221                 if (err)
 222                         return err;
 223
 224                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
 225         }
 226
 227         skcipher_request_set_tfm(skreq, enc);
 228         skcipher_request_set_callback(skreq, aead_request_flags(req),
 229                                       crypto_authenc_encrypt_done, req);
 230         skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
 231
 232         err = crypto_skcipher_encrypt(skreq);
 233         if (err)
 234                 return err;
 235
 236         return crypto_authenc_genicv(req, aead_request_flags(req));
 237 }
 238
 239 static int crypto_authenc_decrypt_tail(struct aead_request *req,
 240                                        unsigned int flags)
 241 {
 242         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 243         struct aead_instance *inst = aead_alg_instance(authenc);
 244         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 245         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 246         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 247         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 248         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 249                                                   ictx->reqoff);
 250         unsigned int authsize = crypto_aead_authsize(authenc);
 251         u8 *ihash = ahreq->result + authsize;
 252         struct scatterlist *src, *dst;
 253
 254         scatterwalk_map_and_copy(ihash, req->src, ahreq->nbytes, authsize, 0);
 255
 256         if (crypto_memneq(ihash, ahreq->result, authsize))
 257                 return -EBADMSG;
 258
 259         src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
 260         dst = src;
 261
 262         if (req->src != req->dst)
 263                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
 264
 265         skcipher_request_set_tfm(skreq, ctx->enc);
 266         skcipher_request_set_callback(skreq, aead_request_flags(req),
 267                                       req->base.complete, req->base.data);
 268         skcipher_request_set_crypt(skreq, src, dst,
 269                                    req->cryptlen - authsize, req->iv);
 270
 271         return crypto_skcipher_decrypt(skreq);
 272 }
 273
 274 static void authenc_verify_ahash_done(struct crypto_async_request *areq,
 275                                       int err)
 276 {
 277         struct aead_request *req = areq->data;
 278
 279         if (err)
 280                 goto out;
 281
 282         err = crypto_authenc_decrypt_tail(req, 0);
 283
 284 out:
 285         authenc_request_complete(req, err);
 286 }
 287
 288 static int crypto_authenc_decrypt(struct aead_request *req)
 289 {
 290         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 291         unsigned int authsize = crypto_aead_authsize(authenc);
 292         struct aead_instance *inst = aead_alg_instance(authenc);
 293         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 294         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 295         struct crypto_ahash *auth = ctx->auth;
 296         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 297         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 298         u8 *hash = areq_ctx->tail;
 299         int err;
 300
 301         hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
 302                            crypto_ahash_alignmask(auth) + 1);
 303
 304         ahash_request_set_tfm(ahreq, auth);
 305         ahash_request_set_crypt(ahreq, req->src, hash,
 306                                 req->assoclen + req->cryptlen - authsize);
 307         ahash_request_set_callback(ahreq, aead_request_flags(req),
 308                                    authenc_verify_ahash_done, req);
 309
 310         err = crypto_ahash_digest(ahreq);
 311         if (err)
 312                 return err;
 313
 314         return crypto_authenc_decrypt_tail(req, aead_request_flags(req));
 315 }
 316
 317 static int crypto_authenc_init_tfm(struct crypto_aead *tfm)
 318 {
 319         struct aead_instance *inst = aead_alg_instance(tfm);
 320         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 321         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
 322         struct crypto_ahash *auth;
 323         struct crypto_skcipher *enc;
 324         struct crypto_sync_skcipher *null;
 325         int err;
 326
 327         auth = crypto_spawn_ahash(&ictx->auth);
 328         if (IS_ERR(auth))
 329                 return PTR_ERR(auth);
 330
 331         enc = crypto_spawn_skcipher(&ictx->enc);
 332         err = PTR_ERR(enc);
 333         if (IS_ERR(enc))
 334                 goto err_free_ahash;
 335
 336         null = crypto_get_default_null_skcipher();
 337         err = PTR_ERR(null);
 338         if (IS_ERR(null))
 339                 goto err_free_skcipher;
 340
 341         ctx->auth = auth;
 342         ctx->enc = enc;
 343         ctx->null = null;
 344
 345         crypto_aead_set_reqsize(
 346                 tfm,
 347                 sizeof(struct authenc_request_ctx) +
 348                 ictx->reqoff +
 349                 max_t(unsigned int,
 350                       crypto_ahash_reqsize(auth) +
 351                       sizeof(struct ahash_request),
 352                       sizeof(struct skcipher_request) +
 353                       crypto_skcipher_reqsize(enc)));
 354
 355         return 0;
 356
 357 err_free_skcipher:
 358         crypto_free_skcipher(enc);
 359 err_free_ahash:
 360         crypto_free_ahash(auth);
 361         return err;
 362 }
 363
 364 static void crypto_authenc_exit_tfm(struct crypto_aead *tfm)
 365 {
 366         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
 367
 368         crypto_free_ahash(ctx->auth);
 369         crypto_free_skcipher(ctx->enc);
 370         crypto_put_default_null_skcipher();
 371 }
 372
 373 static void crypto_authenc_free(struct aead_instance *inst)
 374 {
 375         struct authenc_instance_ctx *ctx = aead_instance_ctx(inst);
 376
 377         crypto_drop_skcipher(&ctx->enc);
 378         crypto_drop_ahash(&ctx->auth);
 379         kfree(inst);
 380 }
 381
 382 static int crypto_authenc_create(struct crypto_template *tmpl,
 383                                  struct rtattr **tb)
 384 {
 385         struct crypto_attr_type *algt;
 386         struct aead_instance *inst;
 387         struct hash_alg_common *auth;
 388         struct crypto_alg *auth_base;
 389         struct skcipher_alg *enc;
 390         struct authenc_instance_ctx *ctx;
 391         const char *enc_name;
 392         int err;
 393
 394         algt = crypto_get_attr_type(tb);
 395         if (IS_ERR(algt))
 396                 return PTR_ERR(algt);
 397
 398         if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
 399                 return -EINVAL;
 400
 401         auth = ahash_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
 402                               CRYPTO_ALG_TYPE_AHASH_MASK |
 403                               crypto_requires_sync(algt->type, algt->mask));
 404         if (IS_ERR(auth))
 405                 return PTR_ERR(auth);
 406
 407         auth_base = &auth->base;
 408
 409         enc_name = crypto_attr_alg_name(tb[2]);
 410         err = PTR_ERR(enc_name);
 411         if (IS_ERR(enc_name))
 412                 goto out_put_auth;
 413
 414         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 415         err = -ENOMEM;
 416         if (!inst)
 417                 goto out_put_auth;
 418
 419         ctx = aead_instance_ctx(inst);
 420
 421         err = crypto_init_ahash_spawn(&ctx->auth, auth,
 422                                       aead_crypto_instance(inst));
 423         if (err)
 424                 goto err_free_inst;
 425
 426         crypto_set_skcipher_spawn(&ctx->enc, aead_crypto_instance(inst));
 427         err = crypto_grab_skcipher(&ctx->enc, enc_name, 0,
 428                                    crypto_requires_sync(algt->type,
 429                                                         algt->mask));
 430         if (err)
 431                 goto err_drop_auth;
 432
 433         enc = crypto_spawn_skcipher_alg(&ctx->enc);
 434
 435         ctx->reqoff = ALIGN(2 * auth->digestsize + auth_base->cra_alignmask,
 436                             auth_base->cra_alignmask + 1);
 437
 438         err = -ENAMETOOLONG;
 439         if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 440                      "authenc(%s,%s)", auth_base->cra_name,
 441                      enc->base.cra_name) >=
 442             CRYPTO_MAX_ALG_NAME)
 443                 goto err_drop_enc;
 444
 445         if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 446                      "authenc(%s,%s)", auth_base->cra_driver_name,
 447                      enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 448                 goto err_drop_enc;
 449
 450         inst->alg.base.cra_flags = (auth_base->cra_flags |
 451                                     enc->base.cra_flags) & CRYPTO_ALG_ASYNC;
 452         inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
 453                                       auth_base->cra_priority;
 454         inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
 455         inst->alg.base.cra_alignmask = auth_base->cra_alignmask |
 456                                        enc->base.cra_alignmask;
 457         inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
 458
 459         inst->alg.ivsize = crypto_skcipher_alg_ivsize(enc);
 460         inst->alg.chunksize = crypto_skcipher_alg_chunksize(enc);
 461         inst->alg.maxauthsize = auth->digestsize;
 462
 463         inst->alg.init = crypto_authenc_init_tfm;
 464         inst->alg.exit = crypto_authenc_exit_tfm;
 465
 466         inst->alg.setkey = crypto_authenc_setkey;
 467         inst->alg.encrypt = crypto_authenc_encrypt;
 468         inst->alg.decrypt = crypto_authenc_decrypt;
 469
 470         inst->free = crypto_authenc_free;
 471
 472         err = aead_register_instance(tmpl, inst);
 473         if (err)
 474                 goto err_drop_enc;
 475
 476 out:
 477         crypto_mod_put(auth_base);
 478         return err;
 479
 480 err_drop_enc:
 481         crypto_drop_skcipher(&ctx->enc);
 482 err_drop_auth:
 483         crypto_drop_ahash(&ctx->auth);
 484 err_free_inst:
 485         kfree(inst);
 486 out_put_auth:
 487         goto out;
 488 }
 489
 490 static struct crypto_template crypto_authenc_tmpl = {
 491         .name = "authenc",
 492         .create = crypto_authenc_create,
 493         .module = THIS_MODULE,
 494 };
 495
 496 static int __init crypto_authenc_module_init(void)
 497 {
 498         return crypto_register_template(&crypto_authenc_tmpl);
 499 }
 500
 501 static void __exit crypto_authenc_module_exit(void)
 502 {
 503         crypto_unregister_template(&crypto_authenc_tmpl);
 504 }
 505
 506 subsys_initcall(crypto_authenc_module_init);
 507 module_exit(crypto_authenc_module_exit);
 508
 509 MODULE_LICENSE("GPL");
 510 MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");
 511 MODULE_ALIAS_CRYPTO("authenc");