crypto/authenc.c

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