crypto/authenc.c

   1 /*
   2  * Authenc: Simple AEAD wrapper for IPsec
   3  *
   4  * Copyright (c) 2007 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/aead.h>
  14 #include <crypto/internal/skcipher.h>
  15 #include <crypto/authenc.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_instance_ctx {
  26         struct crypto_spawn auth;
  27         struct crypto_skcipher_spawn enc;
  28 };
  29
  30 struct crypto_authenc_ctx {
  31         spinlock_t auth_lock;
  32         struct crypto_hash *auth;
  33         struct crypto_ablkcipher *enc;
  34 };
  35
  36 static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
  37                                  unsigned int keylen)
  38 {
  39         unsigned int authkeylen;
  40         unsigned int enckeylen;
  41         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  42         struct crypto_hash *auth = ctx->auth;
  43         struct crypto_ablkcipher *enc = ctx->enc;
  44         struct rtattr *rta = (void *)key;
  45         struct crypto_authenc_key_param *param;
  46         int err = -EINVAL;
  47
  48         if (!RTA_OK(rta, keylen))
  49                 goto badkey;
  50         if (rta->rta_type != CRYPTO_AUTHENC_KEYA_PARAM)
  51                 goto badkey;
  52         if (RTA_PAYLOAD(rta) < sizeof(*param))
  53                 goto badkey;
  54
  55         param = RTA_DATA(rta);
  56         enckeylen = be32_to_cpu(param->enckeylen);
  57
  58         key += RTA_ALIGN(rta->rta_len);
  59         keylen -= RTA_ALIGN(rta->rta_len);
  60
  61         if (keylen < enckeylen)
  62                 goto badkey;
  63
  64         authkeylen = keylen - enckeylen;
  65
  66         crypto_hash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
  67         crypto_hash_set_flags(auth, crypto_aead_get_flags(authenc) &
  68                                     CRYPTO_TFM_REQ_MASK);
  69         err = crypto_hash_setkey(auth, key, authkeylen);
  70         crypto_aead_set_flags(authenc, crypto_hash_get_flags(auth) &
  71                                        CRYPTO_TFM_RES_MASK);
  72
  73         if (err)
  74                 goto out;
  75
  76         crypto_ablkcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
  77         crypto_ablkcipher_set_flags(enc, crypto_aead_get_flags(authenc) &
  78                                          CRYPTO_TFM_REQ_MASK);
  79         err = crypto_ablkcipher_setkey(enc, key + authkeylen, enckeylen);
  80         crypto_aead_set_flags(authenc, crypto_ablkcipher_get_flags(enc) &
  81                                        CRYPTO_TFM_RES_MASK);
  82
  83 out:
  84         return err;
  85
  86 badkey:
  87         crypto_aead_set_flags(authenc, CRYPTO_TFM_RES_BAD_KEY_LEN);
  88         goto out;
  89 }
  90
  91 static void authenc_chain(struct scatterlist *head, struct scatterlist *sg,
  92                           int chain)
  93 {
  94         if (chain) {
  95                 head->length += sg->length;
  96                 sg = scatterwalk_sg_next(sg);
  97         }
  98
  99         if (sg)
 100                 scatterwalk_sg_chain(head, 2, sg);
 101         else
 102                 sg_mark_end(head);
 103 }
 104
 105 static u8 *crypto_authenc_hash(struct aead_request *req, unsigned int flags,
 106                                struct scatterlist *cipher,
 107                                unsigned int cryptlen)
 108 {
 109         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 110         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 111         struct crypto_hash *auth = ctx->auth;
 112         struct hash_desc desc = {
 113                 .tfm = auth,
 114                 .flags = aead_request_flags(req) & flags,
 115         };
 116         u8 *hash = aead_request_ctx(req);
 117         int err;
 118
 119         hash = (u8 *)ALIGN((unsigned long)hash + crypto_hash_alignmask(auth),
 120                            crypto_hash_alignmask(auth) + 1);
 121
 122         spin_lock_bh(&ctx->auth_lock);
 123         err = crypto_hash_init(&desc);
 124         if (err)
 125                 goto auth_unlock;
 126
 127         err = crypto_hash_update(&desc, req->assoc, req->assoclen);
 128         if (err)
 129                 goto auth_unlock;
 130
 131         err = crypto_hash_update(&desc, cipher, cryptlen);
 132         if (err)
 133                 goto auth_unlock;
 134
 135         err = crypto_hash_final(&desc, hash);
 136 auth_unlock:
 137         spin_unlock_bh(&ctx->auth_lock);
 138
 139         if (err)
 140                 return ERR_PTR(err);
 141
 142         return hash;
 143 }
 144
 145 static int crypto_authenc_genicv(struct aead_request *req, u8 *iv,
 146                                  unsigned int flags)
 147 {
 148         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 149         struct scatterlist *dst = req->dst;
 150         struct scatterlist cipher[2];
 151         struct page *dstp;
 152         unsigned int ivsize = crypto_aead_ivsize(authenc);
 153         unsigned int cryptlen;
 154         u8 *vdst;
 155         u8 *hash;
 156
 157         dstp = sg_page(dst);
 158         vdst = PageHighMem(dstp) ? NULL : page_address(dstp) + dst->offset;
 159
 160         sg_init_table(cipher, 2);
 161         sg_set_buf(cipher, iv, ivsize);
 162         authenc_chain(cipher, dst, vdst == iv + ivsize);
 163
 164         cryptlen = req->cryptlen + ivsize;
 165         hash = crypto_authenc_hash(req, flags, cipher, cryptlen);
 166         if (IS_ERR(hash))
 167                 return PTR_ERR(hash);
 168
 169         scatterwalk_map_and_copy(hash, cipher, cryptlen,
 170                                  crypto_aead_authsize(authenc), 1);
 171         return 0;
 172 }
 173
 174 static void crypto_authenc_encrypt_done(struct crypto_async_request *req,
 175                                         int err)
 176 {
 177         if (!err) {
 178                 struct aead_request *areq = req->data;
 179                 struct crypto_aead *authenc = crypto_aead_reqtfm(areq);
 180                 struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 181                 struct ablkcipher_request *abreq = aead_request_ctx(areq);
 182                 u8 *iv = (u8 *)(abreq + 1) +
 183                          crypto_ablkcipher_reqsize(ctx->enc);
 184
 185                 err = crypto_authenc_genicv(areq, iv, 0);
 186         }
 187
 188         aead_request_complete(req->data, err);
 189 }
 190
 191 static int crypto_authenc_encrypt(struct aead_request *req)
 192 {
 193         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 194         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 195         struct ablkcipher_request *abreq = aead_request_ctx(req);
 196         struct crypto_ablkcipher *enc = ctx->enc;
 197         struct scatterlist *dst = req->dst;
 198         unsigned int cryptlen = req->cryptlen;
 199         u8 *iv = (u8 *)(abreq + 1) + crypto_ablkcipher_reqsize(enc);
 200         int err;
 201
 202         ablkcipher_request_set_tfm(abreq, enc);
 203         ablkcipher_request_set_callback(abreq, aead_request_flags(req),
 204                                         crypto_authenc_encrypt_done, req);
 205         ablkcipher_request_set_crypt(abreq, req->src, dst, cryptlen, req->iv);
 206
 207         memcpy(iv, req->iv, crypto_aead_ivsize(authenc));
 208
 209         err = crypto_ablkcipher_encrypt(abreq);
 210         if (err)
 211                 return err;
 212
 213         return crypto_authenc_genicv(req, iv, CRYPTO_TFM_REQ_MAY_SLEEP);
 214 }
 215
 216 static void crypto_authenc_givencrypt_done(struct crypto_async_request *req,
 217                                            int err)
 218 {
 219         if (!err) {
 220                 struct aead_givcrypt_request *greq = req->data;
 221
 222                 err = crypto_authenc_genicv(&greq->areq, greq->giv, 0);
 223         }
 224
 225         aead_request_complete(req->data, err);
 226 }
 227
 228 static int crypto_authenc_givencrypt(struct aead_givcrypt_request *req)
 229 {
 230         struct crypto_aead *authenc = aead_givcrypt_reqtfm(req);
 231         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 232         struct aead_request *areq = &req->areq;
 233         struct skcipher_givcrypt_request *greq = aead_request_ctx(areq);
 234         u8 *iv = req->giv;
 235         int err;
 236
 237         skcipher_givcrypt_set_tfm(greq, ctx->enc);
 238         skcipher_givcrypt_set_callback(greq, aead_request_flags(areq),
 239                                        crypto_authenc_givencrypt_done, areq);
 240         skcipher_givcrypt_set_crypt(greq, areq->src, areq->dst, areq->cryptlen,
 241                                     areq->iv);
 242         skcipher_givcrypt_set_giv(greq, iv, req->seq);
 243
 244         err = crypto_skcipher_givencrypt(greq);
 245         if (err)
 246                 return err;
 247
 248         return crypto_authenc_genicv(areq, iv, CRYPTO_TFM_REQ_MAY_SLEEP);
 249 }
 250
 251 static int crypto_authenc_verify(struct aead_request *req,
 252                                  struct scatterlist *cipher,
 253                                  unsigned int cryptlen)
 254 {
 255         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 256         u8 *ohash;
 257         u8 *ihash;
 258         unsigned int authsize;
 259
 260         ohash = crypto_authenc_hash(req, CRYPTO_TFM_REQ_MAY_SLEEP, cipher,
 261                                     cryptlen);
 262         if (IS_ERR(ohash))
 263                 return PTR_ERR(ohash);
 264
 265         authsize = crypto_aead_authsize(authenc);
 266         ihash = ohash + authsize;
 267         scatterwalk_map_and_copy(ihash, cipher, cryptlen, authsize, 0);
 268         return memcmp(ihash, ohash, authsize) ? -EBADMSG: 0;
 269 }
 270
 271 static int crypto_authenc_iverify(struct aead_request *req, u8 *iv,
 272                                   unsigned int cryptlen)
 273 {
 274         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 275         struct scatterlist *src = req->src;
 276         struct scatterlist cipher[2];
 277         struct page *srcp;
 278         unsigned int ivsize = crypto_aead_ivsize(authenc);
 279         u8 *vsrc;
 280
 281         srcp = sg_page(src);
 282         vsrc = PageHighMem(srcp) ? NULL : page_address(srcp) + src->offset;
 283
 284         sg_init_table(cipher, 2);
 285         sg_set_buf(cipher, iv, ivsize);
 286         authenc_chain(cipher, src, vsrc == iv + ivsize);
 287
 288         return crypto_authenc_verify(req, cipher, cryptlen + ivsize);
 289 }
 290
 291 static int crypto_authenc_decrypt(struct aead_request *req)
 292 {
 293         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 294         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 295         struct ablkcipher_request *abreq = aead_request_ctx(req);
 296         unsigned int cryptlen = req->cryptlen;
 297         unsigned int authsize = crypto_aead_authsize(authenc);
 298         u8 *iv = req->iv;
 299         int err;
 300
 301         if (cryptlen < authsize)
 302                 return -EINVAL;
 303         cryptlen -= authsize;
 304
 305         err = crypto_authenc_iverify(req, iv, cryptlen);
 306         if (err)
 307                 return err;
 308
 309         ablkcipher_request_set_tfm(abreq, ctx->enc);
 310         ablkcipher_request_set_callback(abreq, aead_request_flags(req),
 311                                         req->base.complete, req->base.data);
 312         ablkcipher_request_set_crypt(abreq, req->src, req->dst, cryptlen, iv);
 313
 314         return crypto_ablkcipher_decrypt(abreq);
 315 }
 316
 317 static int crypto_authenc_init_tfm(struct crypto_tfm *tfm)
 318 {
 319         struct crypto_instance *inst = (void *)tfm->__crt_alg;
 320         struct authenc_instance_ctx *ictx = crypto_instance_ctx(inst);
 321         struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
 322         struct crypto_hash *auth;
 323         struct crypto_ablkcipher *enc;
 324         int err;
 325
 326         auth = crypto_spawn_hash(&ictx->auth);
 327         if (IS_ERR(auth))
 328                 return PTR_ERR(auth);
 329
 330         enc = crypto_spawn_skcipher(&ictx->enc);
 331         err = PTR_ERR(enc);
 332         if (IS_ERR(enc))
 333                 goto err_free_hash;
 334
 335         ctx->auth = auth;
 336         ctx->enc = enc;
 337         tfm->crt_aead.reqsize = max_t(unsigned int,
 338                                       (crypto_hash_alignmask(auth) &
 339                                        ~(crypto_tfm_ctx_alignment() - 1)) +
 340                                       crypto_hash_digestsize(auth) * 2,
 341                                       sizeof(struct skcipher_givcrypt_request) +
 342                                       crypto_ablkcipher_reqsize(enc) +
 343                                       crypto_ablkcipher_ivsize(enc));
 344
 345         spin_lock_init(&ctx->auth_lock);
 346
 347         return 0;
 348
 349 err_free_hash:
 350         crypto_free_hash(auth);
 351         return err;
 352 }
 353
 354 static void crypto_authenc_exit_tfm(struct crypto_tfm *tfm)
 355 {
 356         struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
 357
 358         crypto_free_hash(ctx->auth);
 359         crypto_free_ablkcipher(ctx->enc);
 360 }
 361
 362 static struct crypto_instance *crypto_authenc_alloc(struct rtattr **tb)
 363 {
 364         struct crypto_attr_type *algt;
 365         struct crypto_instance *inst;
 366         struct crypto_alg *auth;
 367         struct crypto_alg *enc;
 368         struct authenc_instance_ctx *ctx;
 369         const char *enc_name;
 370         int err;
 371
 372         algt = crypto_get_attr_type(tb);
 373         err = PTR_ERR(algt);
 374         if (IS_ERR(algt))
 375                 return ERR_PTR(err);
 376
 377         if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
 378                 return ERR_PTR(-EINVAL);
 379
 380         auth = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
 381                                CRYPTO_ALG_TYPE_HASH_MASK);
 382         if (IS_ERR(auth))
 383                 return ERR_PTR(PTR_ERR(auth));
 384
 385         enc_name = crypto_attr_alg_name(tb[2]);
 386         err = PTR_ERR(enc_name);
 387         if (IS_ERR(enc_name))
 388                 goto out_put_auth;
 389
 390         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 391         err = -ENOMEM;
 392         if (!inst)
 393                 goto out_put_auth;
 394
 395         ctx = crypto_instance_ctx(inst);
 396
 397         err = crypto_init_spawn(&ctx->auth, auth, inst, CRYPTO_ALG_TYPE_MASK);
 398         if (err)
 399                 goto err_free_inst;
 400
 401         crypto_set_skcipher_spawn(&ctx->enc, inst);
 402         err = crypto_grab_skcipher(&ctx->enc, enc_name, 0,
 403                                    crypto_requires_sync(algt->type,
 404                                                         algt->mask));
 405         if (err)
 406                 goto err_drop_auth;
 407
 408         enc = crypto_skcipher_spawn_alg(&ctx->enc);
 409
 410         err = -ENAMETOOLONG;
 411         if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
 412                      "authenc(%s,%s)", auth->cra_name, enc->cra_name) >=
 413             CRYPTO_MAX_ALG_NAME)
 414                 goto err_drop_enc;
 415
 416         if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 417                      "authenc(%s,%s)", auth->cra_driver_name,
 418                      enc->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 419                 goto err_drop_enc;
 420
 421         inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD;
 422         inst->alg.cra_flags |= enc->cra_flags & CRYPTO_ALG_ASYNC;
 423         inst->alg.cra_priority = enc->cra_priority * 10 + auth->cra_priority;
 424         inst->alg.cra_blocksize = enc->cra_blocksize;
 425         inst->alg.cra_alignmask = auth->cra_alignmask | enc->cra_alignmask;
 426         inst->alg.cra_type = &crypto_aead_type;
 427
 428         inst->alg.cra_aead.ivsize = enc->cra_ablkcipher.ivsize;
 429         inst->alg.cra_aead.maxauthsize = auth->cra_type == &crypto_hash_type ?
 430                                          auth->cra_hash.digestsize :
 431                                          auth->cra_digest.dia_digestsize;
 432
 433         inst->alg.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
 434
 435         inst->alg.cra_init = crypto_authenc_init_tfm;
 436         inst->alg.cra_exit = crypto_authenc_exit_tfm;
 437
 438         inst->alg.cra_aead.setkey = crypto_authenc_setkey;
 439         inst->alg.cra_aead.encrypt = crypto_authenc_encrypt;
 440         inst->alg.cra_aead.decrypt = crypto_authenc_decrypt;
 441         inst->alg.cra_aead.givencrypt = crypto_authenc_givencrypt;
 442
 443 out:
 444         crypto_mod_put(auth);
 445         return inst;
 446
 447 err_drop_enc:
 448         crypto_drop_skcipher(&ctx->enc);
 449 err_drop_auth:
 450         crypto_drop_spawn(&ctx->auth);
 451 err_free_inst:
 452         kfree(inst);
 453 out_put_auth:
 454         inst = ERR_PTR(err);
 455         goto out;
 456 }
 457
 458 static void crypto_authenc_free(struct crypto_instance *inst)
 459 {
 460         struct authenc_instance_ctx *ctx = crypto_instance_ctx(inst);
 461
 462         crypto_drop_skcipher(&ctx->enc);
 463         crypto_drop_spawn(&ctx->auth);
 464         kfree(inst);
 465 }
 466
 467 static struct crypto_template crypto_authenc_tmpl = {
 468         .name = "authenc",
 469         .alloc = crypto_authenc_alloc,
 470         .free = crypto_authenc_free,
 471         .module = THIS_MODULE,
 472 };
 473
 474 static int __init crypto_authenc_module_init(void)
 475 {
 476         return crypto_register_template(&crypto_authenc_tmpl);
 477 }
 478
 479 static void __exit crypto_authenc_module_exit(void)
 480 {
 481         crypto_unregister_template(&crypto_authenc_tmpl);
 482 }
 483
 484 module_init(crypto_authenc_module_init);
 485 module_exit(crypto_authenc_module_exit);
 486
 487 MODULE_LICENSE("GPL");
 488 MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");