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_request *areq = req->data;
 221                 struct skcipher_givcrypt_request *greq = aead_request_ctx(areq);
 222
 223                 err = crypto_authenc_genicv(areq, greq->giv, 0);
 224         }
 225
 226         aead_request_complete(req->data, err);
 227 }
 228
 229 static int crypto_authenc_givencrypt(struct aead_givcrypt_request *req)
 230 {
 231         struct crypto_aead *authenc = aead_givcrypt_reqtfm(req);
 232         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 233         struct aead_request *areq = &req->areq;
 234         struct skcipher_givcrypt_request *greq = aead_request_ctx(areq);
 235         u8 *iv = req->giv;
 236         int err;
 237
 238         skcipher_givcrypt_set_tfm(greq, ctx->enc);
 239         skcipher_givcrypt_set_callback(greq, aead_request_flags(areq),
 240                                        crypto_authenc_givencrypt_done, areq);
 241         skcipher_givcrypt_set_crypt(greq, areq->src, areq->dst, areq->cryptlen,
 242                                     areq->iv);
 243         skcipher_givcrypt_set_giv(greq, iv, req->seq);
 244
 245         err = crypto_skcipher_givencrypt(greq);
 246         if (err)
 247                 return err;
 248
 249         return crypto_authenc_genicv(areq, iv, CRYPTO_TFM_REQ_MAY_SLEEP);
 250 }
 251
 252 static int crypto_authenc_verify(struct aead_request *req,
 253                                  struct scatterlist *cipher,
 254                                  unsigned int cryptlen)
 255 {
 256         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 257         u8 *ohash;
 258         u8 *ihash;
 259         unsigned int authsize;
 260
 261         ohash = crypto_authenc_hash(req, CRYPTO_TFM_REQ_MAY_SLEEP, cipher,
 262                                     cryptlen);
 263         if (IS_ERR(ohash))
 264                 return PTR_ERR(ohash);
 265
 266         authsize = crypto_aead_authsize(authenc);
 267         ihash = ohash + authsize;
 268         scatterwalk_map_and_copy(ihash, cipher, cryptlen, authsize, 0);
 269         return memcmp(ihash, ohash, authsize) ? -EBADMSG: 0;
 270 }
 271
 272 static int crypto_authenc_iverify(struct aead_request *req, u8 *iv,
 273                                   unsigned int cryptlen)
 274 {
 275         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 276         struct scatterlist *src = req->src;
 277         struct scatterlist cipher[2];
 278         struct page *srcp;
 279         unsigned int ivsize = crypto_aead_ivsize(authenc);
 280         u8 *vsrc;
 281
 282         srcp = sg_page(src);
 283         vsrc = PageHighMem(srcp) ? NULL : page_address(srcp) + src->offset;
 284
 285         sg_init_table(cipher, 2);
 286         sg_set_buf(cipher, iv, ivsize);
 287         authenc_chain(cipher, src, vsrc == iv + ivsize);
 288
 289         return crypto_authenc_verify(req, cipher, cryptlen + ivsize);
 290 }
 291
 292 static int crypto_authenc_decrypt(struct aead_request *req)
 293 {
 294         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 295         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 296         struct ablkcipher_request *abreq = aead_request_ctx(req);
 297         unsigned int cryptlen = req->cryptlen;
 298         unsigned int authsize = crypto_aead_authsize(authenc);
 299         u8 *iv = req->iv;
 300         int err;
 301
 302         if (cryptlen < authsize)
 303                 return -EINVAL;
 304         cryptlen -= authsize;
 305
 306         err = crypto_authenc_iverify(req, iv, cryptlen);
 307         if (err)
 308                 return err;
 309
 310         ablkcipher_request_set_tfm(abreq, ctx->enc);
 311         ablkcipher_request_set_callback(abreq, aead_request_flags(req),
 312                                         req->base.complete, req->base.data);
 313         ablkcipher_request_set_crypt(abreq, req->src, req->dst, cryptlen, iv);
 314
 315         return crypto_ablkcipher_decrypt(abreq);
 316 }
 317
 318 static int crypto_authenc_init_tfm(struct crypto_tfm *tfm)
 319 {
 320         struct crypto_instance *inst = (void *)tfm->__crt_alg;
 321         struct authenc_instance_ctx *ictx = crypto_instance_ctx(inst);
 322         struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
 323         struct crypto_hash *auth;
 324         struct crypto_ablkcipher *enc;
 325         int err;
 326
 327         auth = crypto_spawn_hash(&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_hash;
 335
 336         ctx->auth = auth;
 337         ctx->enc = enc;
 338         tfm->crt_aead.reqsize = max_t(unsigned int,
 339                                       (crypto_hash_alignmask(auth) &
 340                                        ~(crypto_tfm_ctx_alignment() - 1)) +
 341                                       crypto_hash_digestsize(auth) * 2,
 342                                       sizeof(struct skcipher_givcrypt_request) +
 343                                       crypto_ablkcipher_reqsize(enc) +
 344                                       crypto_ablkcipher_ivsize(enc));
 345
 346         spin_lock_init(&ctx->auth_lock);
 347
 348         return 0;
 349
 350 err_free_hash:
 351         crypto_free_hash(auth);
 352         return err;
 353 }
 354
 355 static void crypto_authenc_exit_tfm(struct crypto_tfm *tfm)
 356 {
 357         struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
 358
 359         crypto_free_hash(ctx->auth);
 360         crypto_free_ablkcipher(ctx->enc);
 361 }
 362
 363 static struct crypto_instance *crypto_authenc_alloc(struct rtattr **tb)
 364 {
 365         struct crypto_attr_type *algt;
 366         struct crypto_instance *inst;
 367         struct crypto_alg *auth;
 368         struct crypto_alg *enc;
 369         struct authenc_instance_ctx *ctx;
 370         const char *enc_name;
 371         int err;
 372
 373         algt = crypto_get_attr_type(tb);
 374         err = PTR_ERR(algt);
 375         if (IS_ERR(algt))
 376                 return ERR_PTR(err);
 377
 378         if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
 379                 return ERR_PTR(-EINVAL);
 380
 381         auth = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
 382                                CRYPTO_ALG_TYPE_HASH_MASK);
 383         if (IS_ERR(auth))
 384                 return ERR_PTR(PTR_ERR(auth));
 385
 386         enc_name = crypto_attr_alg_name(tb[2]);
 387         err = PTR_ERR(enc_name);
 388         if (IS_ERR(enc_name))
 389                 goto out_put_auth;
 390
 391         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 392         err = -ENOMEM;
 393         if (!inst)
 394                 goto out_put_auth;
 395
 396         ctx = crypto_instance_ctx(inst);
 397
 398         err = crypto_init_spawn(&ctx->auth, auth, inst, CRYPTO_ALG_TYPE_MASK);
 399         if (err)
 400                 goto err_free_inst;
 401
 402         crypto_set_skcipher_spawn(&ctx->enc, inst);
 403         err = crypto_grab_skcipher(&ctx->enc, enc_name, 0,
 404                                    crypto_requires_sync(algt->type,
 405                                                         algt->mask));
 406         if (err)
 407                 goto err_drop_auth;
 408
 409         enc = crypto_skcipher_spawn_alg(&ctx->enc);
 410
 411         err = -ENAMETOOLONG;
 412         if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
 413                      "authenc(%s,%s)", auth->cra_name, enc->cra_name) >=
 414             CRYPTO_MAX_ALG_NAME)
 415                 goto err_drop_enc;
 416
 417         if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 418                      "authenc(%s,%s)", auth->cra_driver_name,
 419                      enc->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 420                 goto err_drop_enc;
 421
 422         inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD;
 423         inst->alg.cra_flags |= enc->cra_flags & CRYPTO_ALG_ASYNC;
 424         inst->alg.cra_priority = enc->cra_priority * 10 + auth->cra_priority;
 425         inst->alg.cra_blocksize = enc->cra_blocksize;
 426         inst->alg.cra_alignmask = auth->cra_alignmask | enc->cra_alignmask;
 427         inst->alg.cra_type = &crypto_aead_type;
 428
 429         inst->alg.cra_aead.ivsize = enc->cra_ablkcipher.ivsize;
 430         inst->alg.cra_aead.maxauthsize = auth->cra_type == &crypto_hash_type ?
 431                                          auth->cra_hash.digestsize :
 432                                          auth->cra_digest.dia_digestsize;
 433
 434         inst->alg.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
 435
 436         inst->alg.cra_init = crypto_authenc_init_tfm;
 437         inst->alg.cra_exit = crypto_authenc_exit_tfm;
 438
 439         inst->alg.cra_aead.setkey = crypto_authenc_setkey;
 440         inst->alg.cra_aead.encrypt = crypto_authenc_encrypt;
 441         inst->alg.cra_aead.decrypt = crypto_authenc_decrypt;
 442         inst->alg.cra_aead.givencrypt = crypto_authenc_givencrypt;
 443
 444 out:
 445         crypto_mod_put(auth);
 446         return inst;
 447
 448 err_drop_enc:
 449         crypto_drop_skcipher(&ctx->enc);
 450 err_drop_auth:
 451         crypto_drop_spawn(&ctx->auth);
 452 err_free_inst:
 453         kfree(inst);
 454 out_put_auth:
 455         inst = ERR_PTR(err);
 456         goto out;
 457 }
 458
 459 static void crypto_authenc_free(struct crypto_instance *inst)
 460 {
 461         struct authenc_instance_ctx *ctx = crypto_instance_ctx(inst);
 462
 463         crypto_drop_skcipher(&ctx->enc);
 464         crypto_drop_spawn(&ctx->auth);
 465         kfree(inst);
 466 }
 467
 468 static struct crypto_template crypto_authenc_tmpl = {
 469         .name = "authenc",
 470         .alloc = crypto_authenc_alloc,
 471         .free = crypto_authenc_free,
 472         .module = THIS_MODULE,
 473 };
 474
 475 static int __init crypto_authenc_module_init(void)
 476 {
 477         return crypto_register_template(&crypto_authenc_tmpl);
 478 }
 479
 480 static void __exit crypto_authenc_module_exit(void)
 481 {
 482         crypto_unregister_template(&crypto_authenc_tmpl);
 483 }
 484
 485 module_init(crypto_authenc_module_init);
 486 module_exit(crypto_authenc_module_exit);
 487
 488 MODULE_LICENSE("GPL");
 489 MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");