linux/crypto/authenc.c
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   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
  27struct authenc_instance_ctx {
  28        struct crypto_ahash_spawn auth;
  29        struct crypto_skcipher_spawn enc;
  30        unsigned int reqoff;
  31};
  32
  33struct crypto_authenc_ctx {
  34        struct crypto_ahash *auth;
  35        struct crypto_skcipher *enc;
  36        struct crypto_skcipher *null;
  37};
  38
  39struct authenc_request_ctx {
  40        struct scatterlist src[2];
  41        struct scatterlist dst[2];
  42        char tail[];
  43};
  44
  45static void authenc_request_complete(struct aead_request *req, int err)
  46{
  47        if (err != -EINPROGRESS)
  48                aead_request_complete(req, err);
  49}
  50
  51int 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        if (RTA_PAYLOAD(rta) < sizeof(*param))
  62                return -EINVAL;
  63
  64        param = RTA_DATA(rta);
  65        keys->enckeylen = be32_to_cpu(param->enckeylen);
  66
  67        key += RTA_ALIGN(rta->rta_len);
  68        keylen -= RTA_ALIGN(rta->rta_len);
  69
  70        if (keylen < keys->enckeylen)
  71                return -EINVAL;
  72
  73        keys->authkeylen = keylen - keys->enckeylen;
  74        keys->authkey = key;
  75        keys->enckey = key + keys->authkeylen;
  76
  77        return 0;
  78}
  79EXPORT_SYMBOL_GPL(crypto_authenc_extractkeys);
  80
  81static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
  82                                 unsigned int keylen)
  83{
  84        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  85        struct crypto_ahash *auth = ctx->auth;
  86        struct crypto_skcipher *enc = ctx->enc;
  87        struct crypto_authenc_keys keys;
  88        int err = -EINVAL;
  89
  90        if (crypto_authenc_extractkeys(&keys, key, keylen) != 0)
  91                goto badkey;
  92
  93        crypto_ahash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
  94        crypto_ahash_set_flags(auth, crypto_aead_get_flags(authenc) &
  95                                    CRYPTO_TFM_REQ_MASK);
  96        err = crypto_ahash_setkey(auth, keys.authkey, keys.authkeylen);
  97        crypto_aead_set_flags(authenc, crypto_ahash_get_flags(auth) &
  98                                       CRYPTO_TFM_RES_MASK);
  99
 100        if (err)
 101                goto out;
 102
 103        crypto_skcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
 104        crypto_skcipher_set_flags(enc, crypto_aead_get_flags(authenc) &
 105                                       CRYPTO_TFM_REQ_MASK);
 106        err = crypto_skcipher_setkey(enc, keys.enckey, keys.enckeylen);
 107        crypto_aead_set_flags(authenc, crypto_skcipher_get_flags(enc) &
 108                                       CRYPTO_TFM_RES_MASK);
 109
 110out:
 111        return err;
 112
 113badkey:
 114        crypto_aead_set_flags(authenc, CRYPTO_TFM_RES_BAD_KEY_LEN);
 115        goto out;
 116}
 117
 118static void authenc_geniv_ahash_done(struct crypto_async_request *areq, int err)
 119{
 120        struct aead_request *req = areq->data;
 121        struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 122        struct aead_instance *inst = aead_alg_instance(authenc);
 123        struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 124        struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 125        struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 126
 127        if (err)
 128                goto out;
 129
 130        scatterwalk_map_and_copy(ahreq->result, req->dst,
 131                                 req->assoclen + req->cryptlen,
 132                                 crypto_aead_authsize(authenc), 1);
 133
 134out:
 135        aead_request_complete(req, err);
 136}
 137
 138static int crypto_authenc_genicv(struct aead_request *req, unsigned int flags)
 139{
 140        struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 141        struct aead_instance *inst = aead_alg_instance(authenc);
 142        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 143        struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 144        struct crypto_ahash *auth = ctx->auth;
 145        struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 146        struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 147        u8 *hash = areq_ctx->tail;
 148        int err;
 149
 150        hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
 151                           crypto_ahash_alignmask(auth) + 1);
 152
 153        ahash_request_set_tfm(ahreq, auth);
 154        ahash_request_set_crypt(ahreq, req->dst, hash,
 155                                req->assoclen + req->cryptlen);
 156        ahash_request_set_callback(ahreq, flags,
 157                                   authenc_geniv_ahash_done, req);
 158
 159        err = crypto_ahash_digest(ahreq);
 160        if (err)
 161                return err;
 162
 163        scatterwalk_map_and_copy(hash, req->dst, req->assoclen + req->cryptlen,
 164                                 crypto_aead_authsize(authenc), 1);
 165
 166        return 0;
 167}
 168
 169static void crypto_authenc_encrypt_done(struct crypto_async_request *req,
 170                                        int err)
 171{
 172        struct aead_request *areq = req->data;
 173
 174        if (err)
 175                goto out;
 176
 177        err = crypto_authenc_genicv(areq, 0);
 178
 179out:
 180        authenc_request_complete(areq, err);
 181}
 182
 183static int crypto_authenc_copy_assoc(struct aead_request *req)
 184{
 185        struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 186        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 187        SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);
 188
 189        skcipher_request_set_tfm(skreq, ctx->null);
 190        skcipher_request_set_callback(skreq, aead_request_flags(req),
 191                                      NULL, NULL);
 192        skcipher_request_set_crypt(skreq, req->src, req->dst, req->assoclen,
 193                                   NULL);
 194
 195        return crypto_skcipher_encrypt(skreq);
 196}
 197
 198static int crypto_authenc_encrypt(struct aead_request *req)
 199{
 200        struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 201        struct aead_instance *inst = aead_alg_instance(authenc);
 202        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 203        struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 204        struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 205        struct crypto_skcipher *enc = ctx->enc;
 206        unsigned int cryptlen = req->cryptlen;
 207        struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 208                                                  ictx->reqoff);
 209        struct scatterlist *src, *dst;
 210        int err;
 211
 212        src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
 213        dst = src;
 214
 215        if (req->src != req->dst) {
 216                err = crypto_authenc_copy_assoc(req);
 217                if (err)
 218                        return err;
 219
 220                dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
 221        }
 222
 223        skcipher_request_set_tfm(skreq, enc);
 224        skcipher_request_set_callback(skreq, aead_request_flags(req),
 225                                      crypto_authenc_encrypt_done, req);
 226        skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
 227
 228        err = crypto_skcipher_encrypt(skreq);
 229        if (err)
 230                return err;
 231
 232        return crypto_authenc_genicv(req, aead_request_flags(req));
 233}
 234
 235static int crypto_authenc_decrypt_tail(struct aead_request *req,
 236                                       unsigned int flags)
 237{
 238        struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 239        struct aead_instance *inst = aead_alg_instance(authenc);
 240        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 241        struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 242        struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 243        struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 244        struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 245                                                  ictx->reqoff);
 246        unsigned int authsize = crypto_aead_authsize(authenc);
 247        u8 *ihash = ahreq->result + authsize;
 248        struct scatterlist *src, *dst;
 249
 250        scatterwalk_map_and_copy(ihash, req->src, ahreq->nbytes, authsize, 0);
 251
 252        if (crypto_memneq(ihash, ahreq->result, authsize))
 253                return -EBADMSG;
 254
 255        src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
 256        dst = src;
 257
 258        if (req->src != req->dst)
 259                dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
 260
 261        skcipher_request_set_tfm(skreq, ctx->enc);
 262        skcipher_request_set_callback(skreq, aead_request_flags(req),
 263                                      req->base.complete, req->base.data);
 264        skcipher_request_set_crypt(skreq, src, dst,
 265                                   req->cryptlen - authsize, req->iv);
 266
 267        return crypto_skcipher_decrypt(skreq);
 268}
 269
 270static void authenc_verify_ahash_done(struct crypto_async_request *areq,
 271                                      int err)
 272{
 273        struct aead_request *req = areq->data;
 274
 275        if (err)
 276                goto out;
 277
 278        err = crypto_authenc_decrypt_tail(req, 0);
 279
 280out:
 281        authenc_request_complete(req, err);
 282}
 283
 284static int crypto_authenc_decrypt(struct aead_request *req)
 285{
 286        struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 287        unsigned int authsize = crypto_aead_authsize(authenc);
 288        struct aead_instance *inst = aead_alg_instance(authenc);
 289        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 290        struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 291        struct crypto_ahash *auth = ctx->auth;
 292        struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 293        struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 294        u8 *hash = areq_ctx->tail;
 295        int err;
 296
 297        hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
 298                           crypto_ahash_alignmask(auth) + 1);
 299
 300        ahash_request_set_tfm(ahreq, auth);
 301        ahash_request_set_crypt(ahreq, req->src, hash,
 302                                req->assoclen + req->cryptlen - authsize);
 303        ahash_request_set_callback(ahreq, aead_request_flags(req),
 304                                   authenc_verify_ahash_done, req);
 305
 306        err = crypto_ahash_digest(ahreq);
 307        if (err)
 308                return err;
 309
 310        return crypto_authenc_decrypt_tail(req, aead_request_flags(req));
 311}
 312
 313static int crypto_authenc_init_tfm(struct crypto_aead *tfm)
 314{
 315        struct aead_instance *inst = aead_alg_instance(tfm);
 316        struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 317        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
 318        struct crypto_ahash *auth;
 319        struct crypto_skcipher *enc;
 320        struct crypto_skcipher *null;
 321        int err;
 322
 323        auth = crypto_spawn_ahash(&ictx->auth);
 324        if (IS_ERR(auth))
 325                return PTR_ERR(auth);
 326
 327        enc = crypto_spawn_skcipher2(&ictx->enc);
 328        err = PTR_ERR(enc);
 329        if (IS_ERR(enc))
 330                goto err_free_ahash;
 331
 332        null = crypto_get_default_null_skcipher2();
 333        err = PTR_ERR(null);
 334        if (IS_ERR(null))
 335                goto err_free_skcipher;
 336
 337        ctx->auth = auth;
 338        ctx->enc = enc;
 339        ctx->null = null;
 340
 341        crypto_aead_set_reqsize(
 342                tfm,
 343                sizeof(struct authenc_request_ctx) +
 344                ictx->reqoff +
 345                max_t(unsigned int,
 346                      crypto_ahash_reqsize(auth) +
 347                      sizeof(struct ahash_request),
 348                      sizeof(struct skcipher_request) +
 349                      crypto_skcipher_reqsize(enc)));
 350
 351        return 0;
 352
 353err_free_skcipher:
 354        crypto_free_skcipher(enc);
 355err_free_ahash:
 356        crypto_free_ahash(auth);
 357        return err;
 358}
 359
 360static void crypto_authenc_exit_tfm(struct crypto_aead *tfm)
 361{
 362        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
 363
 364        crypto_free_ahash(ctx->auth);
 365        crypto_free_skcipher(ctx->enc);
 366        crypto_put_default_null_skcipher2();
 367}
 368
 369static void crypto_authenc_free(struct aead_instance *inst)
 370{
 371        struct authenc_instance_ctx *ctx = aead_instance_ctx(inst);
 372
 373        crypto_drop_skcipher(&ctx->enc);
 374        crypto_drop_ahash(&ctx->auth);
 375        kfree(inst);
 376}
 377
 378static int crypto_authenc_create(struct crypto_template *tmpl,
 379                                 struct rtattr **tb)
 380{
 381        struct crypto_attr_type *algt;
 382        struct aead_instance *inst;
 383        struct hash_alg_common *auth;
 384        struct crypto_alg *auth_base;
 385        struct skcipher_alg *enc;
 386        struct authenc_instance_ctx *ctx;
 387        const char *enc_name;
 388        int err;
 389
 390        algt = crypto_get_attr_type(tb);
 391        if (IS_ERR(algt))
 392                return PTR_ERR(algt);
 393
 394        if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
 395                return -EINVAL;
 396
 397        auth = ahash_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
 398                              CRYPTO_ALG_TYPE_AHASH_MASK |
 399                              crypto_requires_sync(algt->type, algt->mask));
 400        if (IS_ERR(auth))
 401                return PTR_ERR(auth);
 402
 403        auth_base = &auth->base;
 404
 405        enc_name = crypto_attr_alg_name(tb[2]);
 406        err = PTR_ERR(enc_name);
 407        if (IS_ERR(enc_name))
 408                goto out_put_auth;
 409
 410        inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 411        err = -ENOMEM;
 412        if (!inst)
 413                goto out_put_auth;
 414
 415        ctx = aead_instance_ctx(inst);
 416
 417        err = crypto_init_ahash_spawn(&ctx->auth, auth,
 418                                      aead_crypto_instance(inst));
 419        if (err)
 420                goto err_free_inst;
 421
 422        crypto_set_skcipher_spawn(&ctx->enc, aead_crypto_instance(inst));
 423        err = crypto_grab_skcipher2(&ctx->enc, enc_name, 0,
 424                                    crypto_requires_sync(algt->type,
 425                                                         algt->mask));
 426        if (err)
 427                goto err_drop_auth;
 428
 429        enc = crypto_spawn_skcipher_alg(&ctx->enc);
 430
 431        ctx->reqoff = ALIGN(2 * auth->digestsize + auth_base->cra_alignmask,
 432                            auth_base->cra_alignmask + 1);
 433
 434        err = -ENAMETOOLONG;
 435        if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 436                     "authenc(%s,%s)", auth_base->cra_name,
 437                     enc->base.cra_name) >=
 438            CRYPTO_MAX_ALG_NAME)
 439                goto err_drop_enc;
 440
 441        if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 442                     "authenc(%s,%s)", auth_base->cra_driver_name,
 443                     enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 444                goto err_drop_enc;
 445
 446        inst->alg.base.cra_flags = (auth_base->cra_flags |
 447                                    enc->base.cra_flags) & CRYPTO_ALG_ASYNC;
 448        inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
 449                                      auth_base->cra_priority;
 450        inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
 451        inst->alg.base.cra_alignmask = auth_base->cra_alignmask |
 452                                       enc->base.cra_alignmask;
 453        inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
 454
 455        inst->alg.ivsize = crypto_skcipher_alg_ivsize(enc);
 456        inst->alg.chunksize = crypto_skcipher_alg_chunksize(enc);
 457        inst->alg.maxauthsize = auth->digestsize;
 458
 459        inst->alg.init = crypto_authenc_init_tfm;
 460        inst->alg.exit = crypto_authenc_exit_tfm;
 461
 462        inst->alg.setkey = crypto_authenc_setkey;
 463        inst->alg.encrypt = crypto_authenc_encrypt;
 464        inst->alg.decrypt = crypto_authenc_decrypt;
 465
 466        inst->free = crypto_authenc_free;
 467
 468        err = aead_register_instance(tmpl, inst);
 469        if (err)
 470                goto err_drop_enc;
 471
 472out:
 473        crypto_mod_put(auth_base);
 474        return err;
 475
 476err_drop_enc:
 477        crypto_drop_skcipher(&ctx->enc);
 478err_drop_auth:
 479        crypto_drop_ahash(&ctx->auth);
 480err_free_inst:
 481        kfree(inst);
 482out_put_auth:
 483        goto out;
 484}
 485
 486static struct crypto_template crypto_authenc_tmpl = {
 487        .name = "authenc",
 488        .create = crypto_authenc_create,
 489        .module = THIS_MODULE,
 490};
 491
 492static int __init crypto_authenc_module_init(void)
 493{
 494        return crypto_register_template(&crypto_authenc_tmpl);
 495}
 496
 497static void __exit crypto_authenc_module_exit(void)
 498{
 499        crypto_unregister_template(&crypto_authenc_tmpl);
 500}
 501
 502module_init(crypto_authenc_module_init);
 503module_exit(crypto_authenc_module_exit);
 504
 505MODULE_LICENSE("GPL");
 506MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");
 507MODULE_ALIAS_CRYPTO("authenc");
 508