crypto/authenc.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Authenc: Simple AEAD wrapper for IPsec
   4  *
   5  * Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au>
   6  */
   7
   8 #include <crypto/internal/aead.h>
   9 #include <crypto/internal/hash.h>
  10 #include <crypto/internal/skcipher.h>
  11 #include <crypto/authenc.h>
  12 #include <crypto/null.h>
  13 #include <crypto/scatterwalk.h>
  14 #include <linux/err.h>
  15 #include <linux/init.h>
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/rtnetlink.h>
  19 #include <linux/slab.h>
  20 #include <linux/spinlock.h>
  21
  22 struct authenc_instance_ctx {
  23         struct crypto_ahash_spawn auth;
  24         struct crypto_skcipher_spawn enc;
  25         unsigned int reqoff;
  26 };
  27
  28 struct crypto_authenc_ctx {
  29         struct crypto_ahash *auth;
  30         struct crypto_skcipher *enc;
  31         struct crypto_sync_skcipher *null;
  32 };
  33
  34 struct authenc_request_ctx {
  35         struct scatterlist src[2];
  36         struct scatterlist dst[2];
  37         char tail[];
  38 };
  39
  40 static void authenc_request_complete(struct aead_request *req, int err)
  41 {
  42         if (err != -EINPROGRESS)
  43                 aead_request_complete(req, err);
  44 }
  45
  46 int crypto_authenc_extractkeys(struct crypto_authenc_keys *keys, const u8 *key,
  47                                unsigned int keylen)
  48 {
  49         struct rtattr *rta = (struct rtattr *)key;
  50         struct crypto_authenc_key_param *param;
  51
  52         if (!RTA_OK(rta, keylen))
  53                 return -EINVAL;
  54         if (rta->rta_type != CRYPTO_AUTHENC_KEYA_PARAM)
  55                 return -EINVAL;
  56
  57         /*
  58          * RTA_OK() didn't align the rtattr's payload when validating that it
  59          * fits in the buffer.  Yet, the keys should start on the next 4-byte
  60          * aligned boundary.  To avoid confusion, require that the rtattr
  61          * payload be exactly the param struct, which has a 4-byte aligned size.
  62          */
  63         if (RTA_PAYLOAD(rta) != sizeof(*param))
  64                 return -EINVAL;
  65         BUILD_BUG_ON(sizeof(*param) % RTA_ALIGNTO);
  66
  67         param = RTA_DATA(rta);
  68         keys->enckeylen = be32_to_cpu(param->enckeylen);
  69
  70         key += rta->rta_len;
  71         keylen -= rta->rta_len;
  72
  73         if (keylen < keys->enckeylen)
  74                 return -EINVAL;
  75
  76         keys->authkeylen = keylen - keys->enckeylen;
  77         keys->authkey = key;
  78         keys->enckey = key + keys->authkeylen;
  79
  80         return 0;
  81 }
  82 EXPORT_SYMBOL_GPL(crypto_authenc_extractkeys);
  83
  84 static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
  85                                  unsigned int keylen)
  86 {
  87         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  88         struct crypto_ahash *auth = ctx->auth;
  89         struct crypto_skcipher *enc = ctx->enc;
  90         struct crypto_authenc_keys keys;
  91         int err = -EINVAL;
  92
  93         if (crypto_authenc_extractkeys(&keys, key, keylen) != 0)
  94                 goto out;
  95
  96         crypto_ahash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
  97         crypto_ahash_set_flags(auth, crypto_aead_get_flags(authenc) &
  98                                     CRYPTO_TFM_REQ_MASK);
  99         err = crypto_ahash_setkey(auth, keys.authkey, keys.authkeylen);
 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 out:
 108         memzero_explicit(&keys, sizeof(keys));
 109         return err;
 110 }
 111
 112 static void authenc_geniv_ahash_done(void *data, int err)
 113 {
 114         struct aead_request *req = data;
 115         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 116         struct aead_instance *inst = aead_alg_instance(authenc);
 117         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 118         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 119         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 120
 121         if (err)
 122                 goto out;
 123
 124         scatterwalk_map_and_copy(ahreq->result, req->dst,
 125                                  req->assoclen + req->cryptlen,
 126                                  crypto_aead_authsize(authenc), 1);
 127
 128 out:
 129         aead_request_complete(req, err);
 130 }
 131
 132 static int crypto_authenc_genicv(struct aead_request *req, unsigned int flags)
 133 {
 134         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 135         struct aead_instance *inst = aead_alg_instance(authenc);
 136         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 137         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 138         struct crypto_ahash *auth = ctx->auth;
 139         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 140         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 141         u8 *hash = areq_ctx->tail;
 142         int err;
 143
 144         hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
 145                            crypto_ahash_alignmask(auth) + 1);
 146
 147         ahash_request_set_tfm(ahreq, auth);
 148         ahash_request_set_crypt(ahreq, req->dst, hash,
 149                                 req->assoclen + req->cryptlen);
 150         ahash_request_set_callback(ahreq, flags,
 151                                    authenc_geniv_ahash_done, req);
 152
 153         err = crypto_ahash_digest(ahreq);
 154         if (err)
 155                 return err;
 156
 157         scatterwalk_map_and_copy(hash, req->dst, req->assoclen + req->cryptlen,
 158                                  crypto_aead_authsize(authenc), 1);
 159
 160         return 0;
 161 }
 162
 163 static void crypto_authenc_encrypt_done(void *data, int err)
 164 {
 165         struct aead_request *areq = data;
 166
 167         if (err)
 168                 goto out;
 169
 170         err = crypto_authenc_genicv(areq, 0);
 171
 172 out:
 173         authenc_request_complete(areq, err);
 174 }
 175
 176 static int crypto_authenc_copy_assoc(struct aead_request *req)
 177 {
 178         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 179         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 180         SYNC_SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);
 181
 182         skcipher_request_set_sync_tfm(skreq, ctx->null);
 183         skcipher_request_set_callback(skreq, aead_request_flags(req),
 184                                       NULL, NULL);
 185         skcipher_request_set_crypt(skreq, req->src, req->dst, req->assoclen,
 186                                    NULL);
 187
 188         return crypto_skcipher_encrypt(skreq);
 189 }
 190
 191 static int crypto_authenc_encrypt(struct aead_request *req)
 192 {
 193         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 194         struct aead_instance *inst = aead_alg_instance(authenc);
 195         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 196         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 197         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 198         struct crypto_skcipher *enc = ctx->enc;
 199         unsigned int cryptlen = req->cryptlen;
 200         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 201                                                   ictx->reqoff);
 202         struct scatterlist *src, *dst;
 203         int err;
 204
 205         src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
 206         dst = src;
 207
 208         if (req->src != req->dst) {
 209                 err = crypto_authenc_copy_assoc(req);
 210                 if (err)
 211                         return err;
 212
 213                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
 214         }
 215
 216         skcipher_request_set_tfm(skreq, enc);
 217         skcipher_request_set_callback(skreq, aead_request_flags(req),
 218                                       crypto_authenc_encrypt_done, req);
 219         skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
 220
 221         err = crypto_skcipher_encrypt(skreq);
 222         if (err)
 223                 return err;
 224
 225         return crypto_authenc_genicv(req, aead_request_flags(req));
 226 }
 227
 228 static int crypto_authenc_decrypt_tail(struct aead_request *req,
 229                                        unsigned int flags)
 230 {
 231         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 232         struct aead_instance *inst = aead_alg_instance(authenc);
 233         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 234         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 235         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 236         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 237         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 238                                                   ictx->reqoff);
 239         unsigned int authsize = crypto_aead_authsize(authenc);
 240         u8 *ihash = ahreq->result + authsize;
 241         struct scatterlist *src, *dst;
 242
 243         scatterwalk_map_and_copy(ihash, req->src, ahreq->nbytes, authsize, 0);
 244
 245         if (crypto_memneq(ihash, ahreq->result, authsize))
 246                 return -EBADMSG;
 247
 248         src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
 249         dst = src;
 250
 251         if (req->src != req->dst)
 252                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
 253
 254         skcipher_request_set_tfm(skreq, ctx->enc);
 255         skcipher_request_set_callback(skreq, flags,
 256                                       req->base.complete, req->base.data);
 257         skcipher_request_set_crypt(skreq, src, dst,
 258                                    req->cryptlen - authsize, req->iv);
 259
 260         return crypto_skcipher_decrypt(skreq);
 261 }
 262
 263 static void authenc_verify_ahash_done(void *data, int err)
 264 {
 265         struct aead_request *req = data;
 266
 267         if (err)
 268                 goto out;
 269
 270         err = crypto_authenc_decrypt_tail(req, 0);
 271
 272 out:
 273         authenc_request_complete(req, err);
 274 }
 275
 276 static int crypto_authenc_decrypt(struct aead_request *req)
 277 {
 278         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 279         unsigned int authsize = crypto_aead_authsize(authenc);
 280         struct aead_instance *inst = aead_alg_instance(authenc);
 281         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 282         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 283         struct crypto_ahash *auth = ctx->auth;
 284         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 285         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 286         u8 *hash = areq_ctx->tail;
 287         int err;
 288
 289         hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
 290                            crypto_ahash_alignmask(auth) + 1);
 291
 292         ahash_request_set_tfm(ahreq, auth);
 293         ahash_request_set_crypt(ahreq, req->src, hash,
 294                                 req->assoclen + req->cryptlen - authsize);
 295         ahash_request_set_callback(ahreq, aead_request_flags(req),
 296                                    authenc_verify_ahash_done, req);
 297
 298         err = crypto_ahash_digest(ahreq);
 299         if (err)
 300                 return err;
 301
 302         return crypto_authenc_decrypt_tail(req, aead_request_flags(req));
 303 }
 304
 305 static int crypto_authenc_init_tfm(struct crypto_aead *tfm)
 306 {
 307         struct aead_instance *inst = aead_alg_instance(tfm);
 308         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 309         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
 310         struct crypto_ahash *auth;
 311         struct crypto_skcipher *enc;
 312         struct crypto_sync_skcipher *null;
 313         int err;
 314
 315         auth = crypto_spawn_ahash(&ictx->auth);
 316         if (IS_ERR(auth))
 317                 return PTR_ERR(auth);
 318
 319         enc = crypto_spawn_skcipher(&ictx->enc);
 320         err = PTR_ERR(enc);
 321         if (IS_ERR(enc))
 322                 goto err_free_ahash;
 323
 324         null = crypto_get_default_null_skcipher();
 325         err = PTR_ERR(null);
 326         if (IS_ERR(null))
 327                 goto err_free_skcipher;
 328
 329         ctx->auth = auth;
 330         ctx->enc = enc;
 331         ctx->null = null;
 332
 333         crypto_aead_set_reqsize(
 334                 tfm,
 335                 sizeof(struct authenc_request_ctx) +
 336                 ictx->reqoff +
 337                 max_t(unsigned int,
 338                       crypto_ahash_reqsize(auth) +
 339                       sizeof(struct ahash_request),
 340                       sizeof(struct skcipher_request) +
 341                       crypto_skcipher_reqsize(enc)));
 342
 343         return 0;
 344
 345 err_free_skcipher:
 346         crypto_free_skcipher(enc);
 347 err_free_ahash:
 348         crypto_free_ahash(auth);
 349         return err;
 350 }
 351
 352 static void crypto_authenc_exit_tfm(struct crypto_aead *tfm)
 353 {
 354         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
 355
 356         crypto_free_ahash(ctx->auth);
 357         crypto_free_skcipher(ctx->enc);
 358         crypto_put_default_null_skcipher();
 359 }
 360
 361 static void crypto_authenc_free(struct aead_instance *inst)
 362 {
 363         struct authenc_instance_ctx *ctx = aead_instance_ctx(inst);
 364
 365         crypto_drop_skcipher(&ctx->enc);
 366         crypto_drop_ahash(&ctx->auth);
 367         kfree(inst);
 368 }
 369
 370 static int crypto_authenc_create(struct crypto_template *tmpl,
 371                                  struct rtattr **tb)
 372 {
 373         u32 mask;
 374         struct aead_instance *inst;
 375         struct authenc_instance_ctx *ctx;
 376         struct hash_alg_common *auth;
 377         struct crypto_alg *auth_base;
 378         struct skcipher_alg *enc;
 379         int err;
 380
 381         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD, &mask);
 382         if (err)
 383                 return err;
 384
 385         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 386         if (!inst)
 387                 return -ENOMEM;
 388         ctx = aead_instance_ctx(inst);
 389
 390         err = crypto_grab_ahash(&ctx->auth, aead_crypto_instance(inst),
 391                                 crypto_attr_alg_name(tb[1]), 0, mask);
 392         if (err)
 393                 goto err_free_inst;
 394         auth = crypto_spawn_ahash_alg(&ctx->auth);
 395         auth_base = &auth->base;
 396
 397         err = crypto_grab_skcipher(&ctx->enc, aead_crypto_instance(inst),
 398                                    crypto_attr_alg_name(tb[2]), 0, mask);
 399         if (err)
 400                 goto err_free_inst;
 401         enc = crypto_spawn_skcipher_alg(&ctx->enc);
 402
 403         ctx->reqoff = ALIGN(2 * auth->digestsize + auth_base->cra_alignmask,
 404                             auth_base->cra_alignmask + 1);
 405
 406         err = -ENAMETOOLONG;
 407         if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 408                      "authenc(%s,%s)", auth_base->cra_name,
 409                      enc->base.cra_name) >=
 410             CRYPTO_MAX_ALG_NAME)
 411                 goto err_free_inst;
 412
 413         if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 414                      "authenc(%s,%s)", auth_base->cra_driver_name,
 415                      enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 416                 goto err_free_inst;
 417
 418         inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
 419                                       auth_base->cra_priority;
 420         inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
 421         inst->alg.base.cra_alignmask = auth_base->cra_alignmask |
 422                                        enc->base.cra_alignmask;
 423         inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
 424
 425         inst->alg.ivsize = crypto_skcipher_alg_ivsize(enc);
 426         inst->alg.chunksize = crypto_skcipher_alg_chunksize(enc);
 427         inst->alg.maxauthsize = auth->digestsize;
 428
 429         inst->alg.init = crypto_authenc_init_tfm;
 430         inst->alg.exit = crypto_authenc_exit_tfm;
 431
 432         inst->alg.setkey = crypto_authenc_setkey;
 433         inst->alg.encrypt = crypto_authenc_encrypt;
 434         inst->alg.decrypt = crypto_authenc_decrypt;
 435
 436         inst->free = crypto_authenc_free;
 437
 438         err = aead_register_instance(tmpl, inst);
 439         if (err) {
 440 err_free_inst:
 441                 crypto_authenc_free(inst);
 442         }
 443         return err;
 444 }
 445
 446 static struct crypto_template crypto_authenc_tmpl = {
 447         .name = "authenc",
 448         .create = crypto_authenc_create,
 449         .module = THIS_MODULE,
 450 };
 451
 452 static int __init crypto_authenc_module_init(void)
 453 {
 454         return crypto_register_template(&crypto_authenc_tmpl);
 455 }
 456
 457 static void __exit crypto_authenc_module_exit(void)
 458 {
 459         crypto_unregister_template(&crypto_authenc_tmpl);
 460 }
 461
 462 subsys_initcall(crypto_authenc_module_init);
 463 module_exit(crypto_authenc_module_exit);
 464
 465 MODULE_LICENSE("GPL");
 466 MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");
 467 MODULE_ALIAS_CRYPTO("authenc");