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         ahash_request_set_tfm(ahreq, auth);
 145         ahash_request_set_crypt(ahreq, req->dst, hash,
 146                                 req->assoclen + req->cryptlen);
 147         ahash_request_set_callback(ahreq, flags,
 148                                    authenc_geniv_ahash_done, req);
 149
 150         err = crypto_ahash_digest(ahreq);
 151         if (err)
 152                 return err;
 153
 154         scatterwalk_map_and_copy(hash, req->dst, req->assoclen + req->cryptlen,
 155                                  crypto_aead_authsize(authenc), 1);
 156
 157         return 0;
 158 }
 159
 160 static void crypto_authenc_encrypt_done(void *data, int err)
 161 {
 162         struct aead_request *areq = data;
 163
 164         if (err)
 165                 goto out;
 166
 167         err = crypto_authenc_genicv(areq, 0);
 168
 169 out:
 170         authenc_request_complete(areq, err);
 171 }
 172
 173 static int crypto_authenc_copy_assoc(struct aead_request *req)
 174 {
 175         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 176         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 177         SYNC_SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);
 178
 179         skcipher_request_set_sync_tfm(skreq, ctx->null);
 180         skcipher_request_set_callback(skreq, aead_request_flags(req),
 181                                       NULL, NULL);
 182         skcipher_request_set_crypt(skreq, req->src, req->dst, req->assoclen,
 183                                    NULL);
 184
 185         return crypto_skcipher_encrypt(skreq);
 186 }
 187
 188 static int crypto_authenc_encrypt(struct aead_request *req)
 189 {
 190         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 191         struct aead_instance *inst = aead_alg_instance(authenc);
 192         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 193         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 194         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 195         struct crypto_skcipher *enc = ctx->enc;
 196         unsigned int cryptlen = req->cryptlen;
 197         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 198                                                   ictx->reqoff);
 199         struct scatterlist *src, *dst;
 200         int err;
 201
 202         src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
 203         dst = src;
 204
 205         if (req->src != req->dst) {
 206                 err = crypto_authenc_copy_assoc(req);
 207                 if (err)
 208                         return err;
 209
 210                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
 211         }
 212
 213         skcipher_request_set_tfm(skreq, enc);
 214         skcipher_request_set_callback(skreq, aead_request_flags(req),
 215                                       crypto_authenc_encrypt_done, req);
 216         skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
 217
 218         err = crypto_skcipher_encrypt(skreq);
 219         if (err)
 220                 return err;
 221
 222         return crypto_authenc_genicv(req, aead_request_flags(req));
 223 }
 224
 225 static int crypto_authenc_decrypt_tail(struct aead_request *req,
 226                                        unsigned int flags)
 227 {
 228         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 229         struct aead_instance *inst = aead_alg_instance(authenc);
 230         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 231         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 232         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 233         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 234         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 235                                                   ictx->reqoff);
 236         unsigned int authsize = crypto_aead_authsize(authenc);
 237         u8 *ihash = ahreq->result + authsize;
 238         struct scatterlist *src, *dst;
 239
 240         scatterwalk_map_and_copy(ihash, req->src, ahreq->nbytes, authsize, 0);
 241
 242         if (crypto_memneq(ihash, ahreq->result, authsize))
 243                 return -EBADMSG;
 244
 245         src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
 246         dst = src;
 247
 248         if (req->src != req->dst)
 249                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
 250
 251         skcipher_request_set_tfm(skreq, ctx->enc);
 252         skcipher_request_set_callback(skreq, flags,
 253                                       req->base.complete, req->base.data);
 254         skcipher_request_set_crypt(skreq, src, dst,
 255                                    req->cryptlen - authsize, req->iv);
 256
 257         return crypto_skcipher_decrypt(skreq);
 258 }
 259
 260 static void authenc_verify_ahash_done(void *data, int err)
 261 {
 262         struct aead_request *req = data;
 263
 264         if (err)
 265                 goto out;
 266
 267         err = crypto_authenc_decrypt_tail(req, 0);
 268
 269 out:
 270         authenc_request_complete(req, err);
 271 }
 272
 273 static int crypto_authenc_decrypt(struct aead_request *req)
 274 {
 275         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 276         unsigned int authsize = crypto_aead_authsize(authenc);
 277         struct aead_instance *inst = aead_alg_instance(authenc);
 278         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 279         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 280         struct crypto_ahash *auth = ctx->auth;
 281         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 282         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 283         u8 *hash = areq_ctx->tail;
 284         int err;
 285
 286         ahash_request_set_tfm(ahreq, auth);
 287         ahash_request_set_crypt(ahreq, req->src, hash,
 288                                 req->assoclen + req->cryptlen - authsize);
 289         ahash_request_set_callback(ahreq, aead_request_flags(req),
 290                                    authenc_verify_ahash_done, req);
 291
 292         err = crypto_ahash_digest(ahreq);
 293         if (err)
 294                 return err;
 295
 296         return crypto_authenc_decrypt_tail(req, aead_request_flags(req));
 297 }
 298
 299 static int crypto_authenc_init_tfm(struct crypto_aead *tfm)
 300 {
 301         struct aead_instance *inst = aead_alg_instance(tfm);
 302         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 303         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
 304         struct crypto_ahash *auth;
 305         struct crypto_skcipher *enc;
 306         struct crypto_sync_skcipher *null;
 307         int err;
 308
 309         auth = crypto_spawn_ahash(&ictx->auth);
 310         if (IS_ERR(auth))
 311                 return PTR_ERR(auth);
 312
 313         enc = crypto_spawn_skcipher(&ictx->enc);
 314         err = PTR_ERR(enc);
 315         if (IS_ERR(enc))
 316                 goto err_free_ahash;
 317
 318         null = crypto_get_default_null_skcipher();
 319         err = PTR_ERR(null);
 320         if (IS_ERR(null))
 321                 goto err_free_skcipher;
 322
 323         ctx->auth = auth;
 324         ctx->enc = enc;
 325         ctx->null = null;
 326
 327         crypto_aead_set_reqsize(
 328                 tfm,
 329                 sizeof(struct authenc_request_ctx) +
 330                 ictx->reqoff +
 331                 max_t(unsigned int,
 332                       crypto_ahash_reqsize(auth) +
 333                       sizeof(struct ahash_request),
 334                       sizeof(struct skcipher_request) +
 335                       crypto_skcipher_reqsize(enc)));
 336
 337         return 0;
 338
 339 err_free_skcipher:
 340         crypto_free_skcipher(enc);
 341 err_free_ahash:
 342         crypto_free_ahash(auth);
 343         return err;
 344 }
 345
 346 static void crypto_authenc_exit_tfm(struct crypto_aead *tfm)
 347 {
 348         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
 349
 350         crypto_free_ahash(ctx->auth);
 351         crypto_free_skcipher(ctx->enc);
 352         crypto_put_default_null_skcipher();
 353 }
 354
 355 static void crypto_authenc_free(struct aead_instance *inst)
 356 {
 357         struct authenc_instance_ctx *ctx = aead_instance_ctx(inst);
 358
 359         crypto_drop_skcipher(&ctx->enc);
 360         crypto_drop_ahash(&ctx->auth);
 361         kfree(inst);
 362 }
 363
 364 static int crypto_authenc_create(struct crypto_template *tmpl,
 365                                  struct rtattr **tb)
 366 {
 367         u32 mask;
 368         struct aead_instance *inst;
 369         struct authenc_instance_ctx *ctx;
 370         struct skcipher_alg_common *enc;
 371         struct hash_alg_common *auth;
 372         struct crypto_alg *auth_base;
 373         int err;
 374
 375         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD, &mask);
 376         if (err)
 377                 return err;
 378
 379         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 380         if (!inst)
 381                 return -ENOMEM;
 382         ctx = aead_instance_ctx(inst);
 383
 384         err = crypto_grab_ahash(&ctx->auth, aead_crypto_instance(inst),
 385                                 crypto_attr_alg_name(tb[1]), 0, mask);
 386         if (err)
 387                 goto err_free_inst;
 388         auth = crypto_spawn_ahash_alg(&ctx->auth);
 389         auth_base = &auth->base;
 390
 391         err = crypto_grab_skcipher(&ctx->enc, aead_crypto_instance(inst),
 392                                    crypto_attr_alg_name(tb[2]), 0, mask);
 393         if (err)
 394                 goto err_free_inst;
 395         enc = crypto_spawn_skcipher_alg_common(&ctx->enc);
 396
 397         ctx->reqoff = 2 * auth->digestsize;
 398
 399         err = -ENAMETOOLONG;
 400         if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 401                      "authenc(%s,%s)", auth_base->cra_name,
 402                      enc->base.cra_name) >=
 403             CRYPTO_MAX_ALG_NAME)
 404                 goto err_free_inst;
 405
 406         if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 407                      "authenc(%s,%s)", auth_base->cra_driver_name,
 408                      enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 409                 goto err_free_inst;
 410
 411         inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
 412                                       auth_base->cra_priority;
 413         inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
 414         inst->alg.base.cra_alignmask = enc->base.cra_alignmask;
 415         inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
 416
 417         inst->alg.ivsize = enc->ivsize;
 418         inst->alg.chunksize = enc->chunksize;
 419         inst->alg.maxauthsize = auth->digestsize;
 420
 421         inst->alg.init = crypto_authenc_init_tfm;
 422         inst->alg.exit = crypto_authenc_exit_tfm;
 423
 424         inst->alg.setkey = crypto_authenc_setkey;
 425         inst->alg.encrypt = crypto_authenc_encrypt;
 426         inst->alg.decrypt = crypto_authenc_decrypt;
 427
 428         inst->free = crypto_authenc_free;
 429
 430         err = aead_register_instance(tmpl, inst);
 431         if (err) {
 432 err_free_inst:
 433                 crypto_authenc_free(inst);
 434         }
 435         return err;
 436 }
 437
 438 static struct crypto_template crypto_authenc_tmpl = {
 439         .name = "authenc",
 440         .create = crypto_authenc_create,
 441         .module = THIS_MODULE,
 442 };
 443
 444 static int __init crypto_authenc_module_init(void)
 445 {
 446         return crypto_register_template(&crypto_authenc_tmpl);
 447 }
 448
 449 static void __exit crypto_authenc_module_exit(void)
 450 {
 451         crypto_unregister_template(&crypto_authenc_tmpl);
 452 }
 453
 454 subsys_initcall(crypto_authenc_module_init);
 455 module_exit(crypto_authenc_module_exit);
 456
 457 MODULE_LICENSE("GPL");
 458 MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");
 459 MODULE_ALIAS_CRYPTO("authenc");