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/hash.h>
  15 #include <crypto/internal/skcipher.h>
  16 #include <crypto/authenc.h>
  17 #include <crypto/scatterwalk.h>
  18 #include <linux/err.h>
  19 #include <linux/init.h>
  20 #include <linux/kernel.h>
  21 #include <linux/module.h>
  22 #include <linux/rtnetlink.h>
  23 #include <linux/slab.h>
  24 #include <linux/spinlock.h>
  25
  26 struct authenc_instance_ctx {
  27         struct crypto_spawn auth;
  28         struct crypto_skcipher_spawn enc;
  29 };
  30
  31 struct crypto_authenc_ctx {
  32         spinlock_t auth_lock;
  33         struct crypto_hash *auth;
  34         struct crypto_ablkcipher *enc;
  35 };
  36
  37 static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
  38                                  unsigned int keylen)
  39 {
  40         unsigned int authkeylen;
  41         unsigned int enckeylen;
  42         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  43         struct crypto_hash *auth = ctx->auth;
  44         struct crypto_ablkcipher *enc = ctx->enc;
  45         struct rtattr *rta = (void *)key;
  46         struct crypto_authenc_key_param *param;
  47         int err = -EINVAL;
  48
  49         if (!RTA_OK(rta, keylen))
  50                 goto badkey;
  51         if (rta->rta_type != CRYPTO_AUTHENC_KEYA_PARAM)
  52                 goto badkey;
  53         if (RTA_PAYLOAD(rta) < sizeof(*param))
  54                 goto badkey;
  55
  56         param = RTA_DATA(rta);
  57         enckeylen = be32_to_cpu(param->enckeylen);
  58
  59         key += RTA_ALIGN(rta->rta_len);
  60         keylen -= RTA_ALIGN(rta->rta_len);
  61
  62         if (keylen < enckeylen)
  63                 goto badkey;
  64
  65         authkeylen = keylen - enckeylen;
  66
  67         crypto_hash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
  68         crypto_hash_set_flags(auth, crypto_aead_get_flags(authenc) &
  69                                     CRYPTO_TFM_REQ_MASK);
  70         err = crypto_hash_setkey(auth, key, authkeylen);
  71         crypto_aead_set_flags(authenc, crypto_hash_get_flags(auth) &
  72                                        CRYPTO_TFM_RES_MASK);
  73
  74         if (err)
  75                 goto out;
  76
  77         crypto_ablkcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
  78         crypto_ablkcipher_set_flags(enc, crypto_aead_get_flags(authenc) &
  79                                          CRYPTO_TFM_REQ_MASK);
  80         err = crypto_ablkcipher_setkey(enc, key + authkeylen, enckeylen);
  81         crypto_aead_set_flags(authenc, crypto_ablkcipher_get_flags(enc) &
  82                                        CRYPTO_TFM_RES_MASK);
  83
  84 out:
  85         return err;
  86
  87 badkey:
  88         crypto_aead_set_flags(authenc, CRYPTO_TFM_RES_BAD_KEY_LEN);
  89         goto out;
  90 }
  91
  92 static void authenc_chain(struct scatterlist *head, struct scatterlist *sg,
  93                           int chain)
  94 {
  95         if (chain) {
  96                 head->length += sg->length;
  97                 sg = scatterwalk_sg_next(sg);
  98         }
  99
 100         if (sg)
 101                 scatterwalk_sg_chain(head, 2, sg);
 102         else
 103                 sg_mark_end(head);
 104 }
 105
 106 static u8 *crypto_authenc_hash(struct aead_request *req, unsigned int flags,
 107                                struct scatterlist *cipher,
 108                                unsigned int cryptlen)
 109 {
 110         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 111         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 112         struct crypto_hash *auth = ctx->auth;
 113         struct hash_desc desc = {
 114                 .tfm = auth,
 115                 .flags = aead_request_flags(req) & flags,
 116         };
 117         u8 *hash = aead_request_ctx(req);
 118         int err;
 119
 120         hash = (u8 *)ALIGN((unsigned long)hash + crypto_hash_alignmask(auth),
 121                            crypto_hash_alignmask(auth) + 1);
 122
 123         spin_lock_bh(&ctx->auth_lock);
 124         err = crypto_hash_init(&desc);
 125         if (err)
 126                 goto auth_unlock;
 127
 128         err = crypto_hash_update(&desc, req->assoc, req->assoclen);
 129         if (err)
 130                 goto auth_unlock;
 131
 132         err = crypto_hash_update(&desc, cipher, cryptlen);
 133         if (err)
 134                 goto auth_unlock;
 135
 136         err = crypto_hash_final(&desc, hash);
 137 auth_unlock:
 138         spin_unlock_bh(&ctx->auth_lock);
 139
 140         if (err)
 141                 return ERR_PTR(err);
 142
 143         return hash;
 144 }
 145
 146 static int crypto_authenc_genicv(struct aead_request *req, u8 *iv,
 147                                  unsigned int flags)
 148 {
 149         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 150         struct scatterlist *dst = req->dst;
 151         struct scatterlist cipher[2];
 152         struct page *dstp;
 153         unsigned int ivsize = crypto_aead_ivsize(authenc);
 154         unsigned int cryptlen;
 155         u8 *vdst;
 156         u8 *hash;
 157
 158         dstp = sg_page(dst);
 159         vdst = PageHighMem(dstp) ? NULL : page_address(dstp) + dst->offset;
 160
 161         sg_init_table(cipher, 2);
 162         sg_set_buf(cipher, iv, ivsize);
 163         authenc_chain(cipher, dst, vdst == iv + ivsize);
 164
 165         cryptlen = req->cryptlen + ivsize;
 166         hash = crypto_authenc_hash(req, flags, cipher, cryptlen);
 167         if (IS_ERR(hash))
 168                 return PTR_ERR(hash);
 169
 170         scatterwalk_map_and_copy(hash, cipher, cryptlen,
 171                                  crypto_aead_authsize(authenc), 1);
 172         return 0;
 173 }
 174
 175 static void crypto_authenc_encrypt_done(struct crypto_async_request *req,
 176                                         int err)
 177 {
 178         struct aead_request *areq = req->data;
 179
 180         if (!err) {
 181                 struct crypto_aead *authenc = crypto_aead_reqtfm(areq);
 182                 struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 183                 struct ablkcipher_request *abreq = aead_request_ctx(areq);
 184                 u8 *iv = (u8 *)(abreq + 1) +
 185                          crypto_ablkcipher_reqsize(ctx->enc);
 186
 187                 err = crypto_authenc_genicv(areq, iv, 0);
 188         }
 189
 190         aead_request_complete(areq, err);
 191 }
 192
 193 static int crypto_authenc_encrypt(struct aead_request *req)
 194 {
 195         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 196         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 197         struct ablkcipher_request *abreq = aead_request_ctx(req);
 198         struct crypto_ablkcipher *enc = ctx->enc;
 199         struct scatterlist *dst = req->dst;
 200         unsigned int cryptlen = req->cryptlen;
 201         u8 *iv = (u8 *)(abreq + 1) + crypto_ablkcipher_reqsize(enc);
 202         int err;
 203
 204         ablkcipher_request_set_tfm(abreq, enc);
 205         ablkcipher_request_set_callback(abreq, aead_request_flags(req),
 206                                         crypto_authenc_encrypt_done, req);
 207         ablkcipher_request_set_crypt(abreq, req->src, dst, cryptlen, req->iv);
 208
 209         memcpy(iv, req->iv, crypto_aead_ivsize(authenc));
 210
 211         err = crypto_ablkcipher_encrypt(abreq);
 212         if (err)
 213                 return err;
 214
 215         return crypto_authenc_genicv(req, iv, CRYPTO_TFM_REQ_MAY_SLEEP);
 216 }
 217
 218 static void crypto_authenc_givencrypt_done(struct crypto_async_request *req,
 219                                            int err)
 220 {
 221         struct aead_request *areq = req->data;
 222
 223         if (!err) {
 224                 struct skcipher_givcrypt_request *greq = aead_request_ctx(areq);
 225
 226                 err = crypto_authenc_genicv(areq, greq->giv, 0);
 227         }
 228
 229         aead_request_complete(areq, err);
 230 }
 231
 232 static int crypto_authenc_givencrypt(struct aead_givcrypt_request *req)
 233 {
 234         struct crypto_aead *authenc = aead_givcrypt_reqtfm(req);
 235         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 236         struct aead_request *areq = &req->areq;
 237         struct skcipher_givcrypt_request *greq = aead_request_ctx(areq);
 238         u8 *iv = req->giv;
 239         int err;
 240
 241         skcipher_givcrypt_set_tfm(greq, ctx->enc);
 242         skcipher_givcrypt_set_callback(greq, aead_request_flags(areq),
 243                                        crypto_authenc_givencrypt_done, areq);
 244         skcipher_givcrypt_set_crypt(greq, areq->src, areq->dst, areq->cryptlen,
 245                                     areq->iv);
 246         skcipher_givcrypt_set_giv(greq, iv, req->seq);
 247
 248         err = crypto_skcipher_givencrypt(greq);
 249         if (err)
 250                 return err;
 251
 252         return crypto_authenc_genicv(areq, iv, CRYPTO_TFM_REQ_MAY_SLEEP);
 253 }
 254
 255 static int crypto_authenc_verify(struct aead_request *req,
 256                                  struct scatterlist *cipher,
 257                                  unsigned int cryptlen)
 258 {
 259         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 260         u8 *ohash;
 261         u8 *ihash;
 262         unsigned int authsize;
 263
 264         ohash = crypto_authenc_hash(req, CRYPTO_TFM_REQ_MAY_SLEEP, cipher,
 265                                     cryptlen);
 266         if (IS_ERR(ohash))
 267                 return PTR_ERR(ohash);
 268
 269         authsize = crypto_aead_authsize(authenc);
 270         ihash = ohash + authsize;
 271         scatterwalk_map_and_copy(ihash, cipher, cryptlen, authsize, 0);
 272         return memcmp(ihash, ohash, authsize) ? -EBADMSG: 0;
 273 }
 274
 275 static int crypto_authenc_iverify(struct aead_request *req, u8 *iv,
 276                                   unsigned int cryptlen)
 277 {
 278         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 279         struct scatterlist *src = req->src;
 280         struct scatterlist cipher[2];
 281         struct page *srcp;
 282         unsigned int ivsize = crypto_aead_ivsize(authenc);
 283         u8 *vsrc;
 284
 285         srcp = sg_page(src);
 286         vsrc = PageHighMem(srcp) ? NULL : page_address(srcp) + src->offset;
 287
 288         sg_init_table(cipher, 2);
 289         sg_set_buf(cipher, iv, ivsize);
 290         authenc_chain(cipher, src, vsrc == iv + ivsize);
 291
 292         return crypto_authenc_verify(req, cipher, cryptlen + ivsize);
 293 }
 294
 295 static int crypto_authenc_decrypt(struct aead_request *req)
 296 {
 297         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 298         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 299         struct ablkcipher_request *abreq = aead_request_ctx(req);
 300         unsigned int cryptlen = req->cryptlen;
 301         unsigned int authsize = crypto_aead_authsize(authenc);
 302         u8 *iv = req->iv;
 303         int err;
 304
 305         if (cryptlen < authsize)
 306                 return -EINVAL;
 307         cryptlen -= authsize;
 308
 309         err = crypto_authenc_iverify(req, iv, cryptlen);
 310         if (err)
 311                 return err;
 312
 313         ablkcipher_request_set_tfm(abreq, ctx->enc);
 314         ablkcipher_request_set_callback(abreq, aead_request_flags(req),
 315                                         req->base.complete, req->base.data);
 316         ablkcipher_request_set_crypt(abreq, req->src, req->dst, cryptlen, iv);
 317
 318         return crypto_ablkcipher_decrypt(abreq);
 319 }
 320
 321 static int crypto_authenc_init_tfm(struct crypto_tfm *tfm)
 322 {
 323         struct crypto_instance *inst = (void *)tfm->__crt_alg;
 324         struct authenc_instance_ctx *ictx = crypto_instance_ctx(inst);
 325         struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
 326         struct crypto_hash *auth;
 327         struct crypto_ablkcipher *enc;
 328         int err;
 329
 330         auth = crypto_spawn_hash(&ictx->auth);
 331         if (IS_ERR(auth))
 332                 return PTR_ERR(auth);
 333
 334         enc = crypto_spawn_skcipher(&ictx->enc);
 335         err = PTR_ERR(enc);
 336         if (IS_ERR(enc))
 337                 goto err_free_hash;
 338
 339         ctx->auth = auth;
 340         ctx->enc = enc;
 341         tfm->crt_aead.reqsize = max_t(unsigned int,
 342                                       (crypto_hash_alignmask(auth) &
 343                                        ~(crypto_tfm_ctx_alignment() - 1)) +
 344                                       crypto_hash_digestsize(auth) * 2,
 345                                       sizeof(struct skcipher_givcrypt_request) +
 346                                       crypto_ablkcipher_reqsize(enc) +
 347                                       crypto_ablkcipher_ivsize(enc));
 348
 349         spin_lock_init(&ctx->auth_lock);
 350
 351         return 0;
 352
 353 err_free_hash:
 354         crypto_free_hash(auth);
 355         return err;
 356 }
 357
 358 static void crypto_authenc_exit_tfm(struct crypto_tfm *tfm)
 359 {
 360         struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
 361
 362         crypto_free_hash(ctx->auth);
 363         crypto_free_ablkcipher(ctx->enc);
 364 }
 365
 366 static struct crypto_instance *crypto_authenc_alloc(struct rtattr **tb)
 367 {
 368         struct crypto_attr_type *algt;
 369         struct crypto_instance *inst;
 370         struct crypto_alg *auth;
 371         struct crypto_alg *enc;
 372         struct authenc_instance_ctx *ctx;
 373         const char *enc_name;
 374         int err;
 375
 376         algt = crypto_get_attr_type(tb);
 377         err = PTR_ERR(algt);
 378         if (IS_ERR(algt))
 379                 return ERR_PTR(err);
 380
 381         if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
 382                 return ERR_PTR(-EINVAL);
 383
 384         auth = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
 385                                CRYPTO_ALG_TYPE_HASH_MASK);
 386         if (IS_ERR(auth))
 387                 return ERR_PTR(PTR_ERR(auth));
 388
 389         enc_name = crypto_attr_alg_name(tb[2]);
 390         err = PTR_ERR(enc_name);
 391         if (IS_ERR(enc_name))
 392                 goto out_put_auth;
 393
 394         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 395         err = -ENOMEM;
 396         if (!inst)
 397                 goto out_put_auth;
 398
 399         ctx = crypto_instance_ctx(inst);
 400
 401         err = crypto_init_spawn(&ctx->auth, auth, inst, CRYPTO_ALG_TYPE_MASK);
 402         if (err)
 403                 goto err_free_inst;
 404
 405         crypto_set_skcipher_spawn(&ctx->enc, inst);
 406         err = crypto_grab_skcipher(&ctx->enc, enc_name, 0,
 407                                    crypto_requires_sync(algt->type,
 408                                                         algt->mask));
 409         if (err)
 410                 goto err_drop_auth;
 411
 412         enc = crypto_skcipher_spawn_alg(&ctx->enc);
 413
 414         err = -ENAMETOOLONG;
 415         if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
 416                      "authenc(%s,%s)", auth->cra_name, enc->cra_name) >=
 417             CRYPTO_MAX_ALG_NAME)
 418                 goto err_drop_enc;
 419
 420         if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 421                      "authenc(%s,%s)", auth->cra_driver_name,
 422                      enc->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 423                 goto err_drop_enc;
 424
 425         inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD;
 426         inst->alg.cra_flags |= enc->cra_flags & CRYPTO_ALG_ASYNC;
 427         inst->alg.cra_priority = enc->cra_priority * 10 + auth->cra_priority;
 428         inst->alg.cra_blocksize = enc->cra_blocksize;
 429         inst->alg.cra_alignmask = auth->cra_alignmask | enc->cra_alignmask;
 430         inst->alg.cra_type = &crypto_aead_type;
 431
 432         inst->alg.cra_aead.ivsize = enc->cra_ablkcipher.ivsize;
 433         inst->alg.cra_aead.maxauthsize = auth->cra_type == &crypto_hash_type ?
 434                                          auth->cra_hash.digestsize :
 435                                          auth->cra_type ?
 436                                          __crypto_shash_alg(auth)->digestsize :
 437                                          auth->cra_digest.dia_digestsize;
 438
 439         inst->alg.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
 440
 441         inst->alg.cra_init = crypto_authenc_init_tfm;
 442         inst->alg.cra_exit = crypto_authenc_exit_tfm;
 443
 444         inst->alg.cra_aead.setkey = crypto_authenc_setkey;
 445         inst->alg.cra_aead.encrypt = crypto_authenc_encrypt;
 446         inst->alg.cra_aead.decrypt = crypto_authenc_decrypt;
 447         inst->alg.cra_aead.givencrypt = crypto_authenc_givencrypt;
 448
 449 out:
 450         crypto_mod_put(auth);
 451         return inst;
 452
 453 err_drop_enc:
 454         crypto_drop_skcipher(&ctx->enc);
 455 err_drop_auth:
 456         crypto_drop_spawn(&ctx->auth);
 457 err_free_inst:
 458         kfree(inst);
 459 out_put_auth:
 460         inst = ERR_PTR(err);
 461         goto out;
 462 }
 463
 464 static void crypto_authenc_free(struct crypto_instance *inst)
 465 {
 466         struct authenc_instance_ctx *ctx = crypto_instance_ctx(inst);
 467
 468         crypto_drop_skcipher(&ctx->enc);
 469         crypto_drop_spawn(&ctx->auth);
 470         kfree(inst);
 471 }
 472
 473 static struct crypto_template crypto_authenc_tmpl = {
 474         .name = "authenc",
 475         .alloc = crypto_authenc_alloc,
 476         .free = crypto_authenc_free,
 477         .module = THIS_MODULE,
 478 };
 479
 480 static int __init crypto_authenc_module_init(void)
 481 {
 482         return crypto_register_template(&crypto_authenc_tmpl);
 483 }
 484
 485 static void __exit crypto_authenc_module_exit(void)
 486 {
 487         crypto_unregister_template(&crypto_authenc_tmpl);
 488 }
 489
 490 module_init(crypto_authenc_module_init);
 491 module_exit(crypto_authenc_module_exit);
 492
 493 MODULE_LICENSE("GPL");
 494 MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");