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         struct aead_request *areq = req->data;
 178
 179         if (!err) {
 180                 struct crypto_aead *authenc = crypto_aead_reqtfm(areq);
 181                 struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 182                 struct ablkcipher_request *abreq = aead_request_ctx(areq);
 183                 u8 *iv = (u8 *)(abreq + 1) +
 184                          crypto_ablkcipher_reqsize(ctx->enc);
 185
 186                 err = crypto_authenc_genicv(areq, iv, 0);
 187         }
 188
 189         aead_request_complete(areq, err);
 190 }
 191
 192 static int crypto_authenc_encrypt(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 ablkcipher_request *abreq = aead_request_ctx(req);
 197         struct crypto_ablkcipher *enc = ctx->enc;
 198         struct scatterlist *dst = req->dst;
 199         unsigned int cryptlen = req->cryptlen;
 200         u8 *iv = (u8 *)(abreq + 1) + crypto_ablkcipher_reqsize(enc);
 201         int err;
 202
 203         ablkcipher_request_set_tfm(abreq, enc);
 204         ablkcipher_request_set_callback(abreq, aead_request_flags(req),
 205                                         crypto_authenc_encrypt_done, req);
 206         ablkcipher_request_set_crypt(abreq, req->src, dst, cryptlen, req->iv);
 207
 208         memcpy(iv, req->iv, crypto_aead_ivsize(authenc));
 209
 210         err = crypto_ablkcipher_encrypt(abreq);
 211         if (err)
 212                 return err;
 213
 214         return crypto_authenc_genicv(req, iv, CRYPTO_TFM_REQ_MAY_SLEEP);
 215 }
 216
 217 static void crypto_authenc_givencrypt_done(struct crypto_async_request *req,
 218                                            int err)
 219 {
 220         struct aead_request *areq = req->data;
 221
 222         if (!err) {
 223                 struct skcipher_givcrypt_request *greq = aead_request_ctx(areq);
 224
 225                 err = crypto_authenc_genicv(areq, greq->giv, 0);
 226         }
 227
 228         aead_request_complete(areq, err);
 229 }
 230
 231 static int crypto_authenc_givencrypt(struct aead_givcrypt_request *req)
 232 {
 233         struct crypto_aead *authenc = aead_givcrypt_reqtfm(req);
 234         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 235         struct aead_request *areq = &req->areq;
 236         struct skcipher_givcrypt_request *greq = aead_request_ctx(areq);
 237         u8 *iv = req->giv;
 238         int err;
 239
 240         skcipher_givcrypt_set_tfm(greq, ctx->enc);
 241         skcipher_givcrypt_set_callback(greq, aead_request_flags(areq),
 242                                        crypto_authenc_givencrypt_done, areq);
 243         skcipher_givcrypt_set_crypt(greq, areq->src, areq->dst, areq->cryptlen,
 244                                     areq->iv);
 245         skcipher_givcrypt_set_giv(greq, iv, req->seq);
 246
 247         err = crypto_skcipher_givencrypt(greq);
 248         if (err)
 249                 return err;
 250
 251         return crypto_authenc_genicv(areq, iv, CRYPTO_TFM_REQ_MAY_SLEEP);
 252 }
 253
 254 static int crypto_authenc_verify(struct aead_request *req,
 255                                  struct scatterlist *cipher,
 256                                  unsigned int cryptlen)
 257 {
 258         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 259         u8 *ohash;
 260         u8 *ihash;
 261         unsigned int authsize;
 262
 263         ohash = crypto_authenc_hash(req, CRYPTO_TFM_REQ_MAY_SLEEP, cipher,
 264                                     cryptlen);
 265         if (IS_ERR(ohash))
 266                 return PTR_ERR(ohash);
 267
 268         authsize = crypto_aead_authsize(authenc);
 269         ihash = ohash + authsize;
 270         scatterwalk_map_and_copy(ihash, cipher, cryptlen, authsize, 0);
 271         return memcmp(ihash, ohash, authsize) ? -EBADMSG: 0;
 272 }
 273
 274 static int crypto_authenc_iverify(struct aead_request *req, u8 *iv,
 275                                   unsigned int cryptlen)
 276 {
 277         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 278         struct scatterlist *src = req->src;
 279         struct scatterlist cipher[2];
 280         struct page *srcp;
 281         unsigned int ivsize = crypto_aead_ivsize(authenc);
 282         u8 *vsrc;
 283
 284         srcp = sg_page(src);
 285         vsrc = PageHighMem(srcp) ? NULL : page_address(srcp) + src->offset;
 286
 287         sg_init_table(cipher, 2);
 288         sg_set_buf(cipher, iv, ivsize);
 289         authenc_chain(cipher, src, vsrc == iv + ivsize);
 290
 291         return crypto_authenc_verify(req, cipher, cryptlen + ivsize);
 292 }
 293
 294 static int crypto_authenc_decrypt(struct aead_request *req)
 295 {
 296         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 297         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 298         struct ablkcipher_request *abreq = aead_request_ctx(req);
 299         unsigned int cryptlen = req->cryptlen;
 300         unsigned int authsize = crypto_aead_authsize(authenc);
 301         u8 *iv = req->iv;
 302         int err;
 303
 304         if (cryptlen < authsize)
 305                 return -EINVAL;
 306         cryptlen -= authsize;
 307
 308         err = crypto_authenc_iverify(req, iv, cryptlen);
 309         if (err)
 310                 return err;
 311
 312         ablkcipher_request_set_tfm(abreq, ctx->enc);
 313         ablkcipher_request_set_callback(abreq, aead_request_flags(req),
 314                                         req->base.complete, req->base.data);
 315         ablkcipher_request_set_crypt(abreq, req->src, req->dst, cryptlen, iv);
 316
 317         return crypto_ablkcipher_decrypt(abreq);
 318 }
 319
 320 static int crypto_authenc_init_tfm(struct crypto_tfm *tfm)
 321 {
 322         struct crypto_instance *inst = (void *)tfm->__crt_alg;
 323         struct authenc_instance_ctx *ictx = crypto_instance_ctx(inst);
 324         struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
 325         struct crypto_hash *auth;
 326         struct crypto_ablkcipher *enc;
 327         int err;
 328
 329         auth = crypto_spawn_hash(&ictx->auth);
 330         if (IS_ERR(auth))
 331                 return PTR_ERR(auth);
 332
 333         enc = crypto_spawn_skcipher(&ictx->enc);
 334         err = PTR_ERR(enc);
 335         if (IS_ERR(enc))
 336                 goto err_free_hash;
 337
 338         ctx->auth = auth;
 339         ctx->enc = enc;
 340         tfm->crt_aead.reqsize = max_t(unsigned int,
 341                                       (crypto_hash_alignmask(auth) &
 342                                        ~(crypto_tfm_ctx_alignment() - 1)) +
 343                                       crypto_hash_digestsize(auth) * 2,
 344                                       sizeof(struct skcipher_givcrypt_request) +
 345                                       crypto_ablkcipher_reqsize(enc) +
 346                                       crypto_ablkcipher_ivsize(enc));
 347
 348         spin_lock_init(&ctx->auth_lock);
 349
 350         return 0;
 351
 352 err_free_hash:
 353         crypto_free_hash(auth);
 354         return err;
 355 }
 356
 357 static void crypto_authenc_exit_tfm(struct crypto_tfm *tfm)
 358 {
 359         struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
 360
 361         crypto_free_hash(ctx->auth);
 362         crypto_free_ablkcipher(ctx->enc);
 363 }
 364
 365 static struct crypto_instance *crypto_authenc_alloc(struct rtattr **tb)
 366 {
 367         struct crypto_attr_type *algt;
 368         struct crypto_instance *inst;
 369         struct crypto_alg *auth;
 370         struct crypto_alg *enc;
 371         struct authenc_instance_ctx *ctx;
 372         const char *enc_name;
 373         int err;
 374
 375         algt = crypto_get_attr_type(tb);
 376         err = PTR_ERR(algt);
 377         if (IS_ERR(algt))
 378                 return ERR_PTR(err);
 379
 380         if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
 381                 return ERR_PTR(-EINVAL);
 382
 383         auth = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
 384                                CRYPTO_ALG_TYPE_HASH_MASK);
 385         if (IS_ERR(auth))
 386                 return ERR_PTR(PTR_ERR(auth));
 387
 388         enc_name = crypto_attr_alg_name(tb[2]);
 389         err = PTR_ERR(enc_name);
 390         if (IS_ERR(enc_name))
 391                 goto out_put_auth;
 392
 393         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 394         err = -ENOMEM;
 395         if (!inst)
 396                 goto out_put_auth;
 397
 398         ctx = crypto_instance_ctx(inst);
 399
 400         err = crypto_init_spawn(&ctx->auth, auth, inst, CRYPTO_ALG_TYPE_MASK);
 401         if (err)
 402                 goto err_free_inst;
 403
 404         crypto_set_skcipher_spawn(&ctx->enc, inst);
 405         err = crypto_grab_skcipher(&ctx->enc, enc_name, 0,
 406                                    crypto_requires_sync(algt->type,
 407                                                         algt->mask));
 408         if (err)
 409                 goto err_drop_auth;
 410
 411         enc = crypto_skcipher_spawn_alg(&ctx->enc);
 412
 413         err = -ENAMETOOLONG;
 414         if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
 415                      "authenc(%s,%s)", auth->cra_name, enc->cra_name) >=
 416             CRYPTO_MAX_ALG_NAME)
 417                 goto err_drop_enc;
 418
 419         if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 420                      "authenc(%s,%s)", auth->cra_driver_name,
 421                      enc->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 422                 goto err_drop_enc;
 423
 424         inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD;
 425         inst->alg.cra_flags |= enc->cra_flags & CRYPTO_ALG_ASYNC;
 426         inst->alg.cra_priority = enc->cra_priority * 10 + auth->cra_priority;
 427         inst->alg.cra_blocksize = enc->cra_blocksize;
 428         inst->alg.cra_alignmask = auth->cra_alignmask | enc->cra_alignmask;
 429         inst->alg.cra_type = &crypto_aead_type;
 430
 431         inst->alg.cra_aead.ivsize = enc->cra_ablkcipher.ivsize;
 432         inst->alg.cra_aead.maxauthsize = auth->cra_type == &crypto_hash_type ?
 433                                          auth->cra_hash.digestsize :
 434                                          auth->cra_digest.dia_digestsize;
 435
 436         inst->alg.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
 437
 438         inst->alg.cra_init = crypto_authenc_init_tfm;
 439         inst->alg.cra_exit = crypto_authenc_exit_tfm;
 440
 441         inst->alg.cra_aead.setkey = crypto_authenc_setkey;
 442         inst->alg.cra_aead.encrypt = crypto_authenc_encrypt;
 443         inst->alg.cra_aead.decrypt = crypto_authenc_decrypt;
 444         inst->alg.cra_aead.givencrypt = crypto_authenc_givencrypt;
 445
 446 out:
 447         crypto_mod_put(auth);
 448         return inst;
 449
 450 err_drop_enc:
 451         crypto_drop_skcipher(&ctx->enc);
 452 err_drop_auth:
 453         crypto_drop_spawn(&ctx->auth);
 454 err_free_inst:
 455         kfree(inst);
 456 out_put_auth:
 457         inst = ERR_PTR(err);
 458         goto out;
 459 }
 460
 461 static void crypto_authenc_free(struct crypto_instance *inst)
 462 {
 463         struct authenc_instance_ctx *ctx = crypto_instance_ctx(inst);
 464
 465         crypto_drop_skcipher(&ctx->enc);
 466         crypto_drop_spawn(&ctx->auth);
 467         kfree(inst);
 468 }
 469
 470 static struct crypto_template crypto_authenc_tmpl = {
 471         .name = "authenc",
 472         .alloc = crypto_authenc_alloc,
 473         .free = crypto_authenc_free,
 474         .module = THIS_MODULE,
 475 };
 476
 477 static int __init crypto_authenc_module_init(void)
 478 {
 479         return crypto_register_template(&crypto_authenc_tmpl);
 480 }
 481
 482 static void __exit crypto_authenc_module_exit(void)
 483 {
 484         crypto_unregister_template(&crypto_authenc_tmpl);
 485 }
 486
 487 module_init(crypto_authenc_module_init);
 488 module_exit(crypto_authenc_module_exit);
 489
 490 MODULE_LICENSE("GPL");
 491 MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");