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(struct crypto_async_request *areq, int err)
 113 {
 114         struct aead_request *req = areq->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(struct crypto_async_request *req,
 164                                         int err)
 165 {
 166         struct aead_request *areq = req->data;
 167
 168         if (err)
 169                 goto out;
 170
 171         err = crypto_authenc_genicv(areq, 0);
 172
 173 out:
 174         authenc_request_complete(areq, err);
 175 }
 176
 177 static int crypto_authenc_copy_assoc(struct aead_request *req)
 178 {
 179         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 180         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 181         SYNC_SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);
 182
 183         skcipher_request_set_sync_tfm(skreq, ctx->null);
 184         skcipher_request_set_callback(skreq, aead_request_flags(req),
 185                                       NULL, NULL);
 186         skcipher_request_set_crypt(skreq, req->src, req->dst, req->assoclen,
 187                                    NULL);
 188
 189         return crypto_skcipher_encrypt(skreq);
 190 }
 191
 192 static int crypto_authenc_encrypt(struct aead_request *req)
 193 {
 194         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 195         struct aead_instance *inst = aead_alg_instance(authenc);
 196         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 197         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 198         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 199         struct crypto_skcipher *enc = ctx->enc;
 200         unsigned int cryptlen = req->cryptlen;
 201         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 202                                                   ictx->reqoff);
 203         struct scatterlist *src, *dst;
 204         int err;
 205
 206         src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
 207         dst = src;
 208
 209         if (req->src != req->dst) {
 210                 err = crypto_authenc_copy_assoc(req);
 211                 if (err)
 212                         return err;
 213
 214                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
 215         }
 216
 217         skcipher_request_set_tfm(skreq, enc);
 218         skcipher_request_set_callback(skreq, aead_request_flags(req),
 219                                       crypto_authenc_encrypt_done, req);
 220         skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
 221
 222         err = crypto_skcipher_encrypt(skreq);
 223         if (err)
 224                 return err;
 225
 226         return crypto_authenc_genicv(req, aead_request_flags(req));
 227 }
 228
 229 static int crypto_authenc_decrypt_tail(struct aead_request *req,
 230                                        unsigned int flags)
 231 {
 232         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 233         struct aead_instance *inst = aead_alg_instance(authenc);
 234         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 235         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 236         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 237         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 238         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 239                                                   ictx->reqoff);
 240         unsigned int authsize = crypto_aead_authsize(authenc);
 241         u8 *ihash = ahreq->result + authsize;
 242         struct scatterlist *src, *dst;
 243
 244         scatterwalk_map_and_copy(ihash, req->src, ahreq->nbytes, authsize, 0);
 245
 246         if (crypto_memneq(ihash, ahreq->result, authsize))
 247                 return -EBADMSG;
 248
 249         src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
 250         dst = src;
 251
 252         if (req->src != req->dst)
 253                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
 254
 255         skcipher_request_set_tfm(skreq, ctx->enc);
 256         skcipher_request_set_callback(skreq, aead_request_flags(req),
 257                                       req->base.complete, req->base.data);
 258         skcipher_request_set_crypt(skreq, src, dst,
 259                                    req->cryptlen - authsize, req->iv);
 260
 261         return crypto_skcipher_decrypt(skreq);
 262 }
 263
 264 static void authenc_verify_ahash_done(struct crypto_async_request *areq,
 265                                       int err)
 266 {
 267         struct aead_request *req = areq->data;
 268
 269         if (err)
 270                 goto out;
 271
 272         err = crypto_authenc_decrypt_tail(req, 0);
 273
 274 out:
 275         authenc_request_complete(req, err);
 276 }
 277
 278 static int crypto_authenc_decrypt(struct aead_request *req)
 279 {
 280         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 281         unsigned int authsize = crypto_aead_authsize(authenc);
 282         struct aead_instance *inst = aead_alg_instance(authenc);
 283         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 284         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 285         struct crypto_ahash *auth = ctx->auth;
 286         struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
 287         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
 288         u8 *hash = areq_ctx->tail;
 289         int err;
 290
 291         hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
 292                            crypto_ahash_alignmask(auth) + 1);
 293
 294         ahash_request_set_tfm(ahreq, auth);
 295         ahash_request_set_crypt(ahreq, req->src, hash,
 296                                 req->assoclen + req->cryptlen - authsize);
 297         ahash_request_set_callback(ahreq, aead_request_flags(req),
 298                                    authenc_verify_ahash_done, req);
 299
 300         err = crypto_ahash_digest(ahreq);
 301         if (err)
 302                 return err;
 303
 304         return crypto_authenc_decrypt_tail(req, aead_request_flags(req));
 305 }
 306
 307 static int crypto_authenc_init_tfm(struct crypto_aead *tfm)
 308 {
 309         struct aead_instance *inst = aead_alg_instance(tfm);
 310         struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 311         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
 312         struct crypto_ahash *auth;
 313         struct crypto_skcipher *enc;
 314         struct crypto_sync_skcipher *null;
 315         int err;
 316
 317         auth = crypto_spawn_ahash(&ictx->auth);
 318         if (IS_ERR(auth))
 319                 return PTR_ERR(auth);
 320
 321         enc = crypto_spawn_skcipher(&ictx->enc);
 322         err = PTR_ERR(enc);
 323         if (IS_ERR(enc))
 324                 goto err_free_ahash;
 325
 326         null = crypto_get_default_null_skcipher();
 327         err = PTR_ERR(null);
 328         if (IS_ERR(null))
 329                 goto err_free_skcipher;
 330
 331         ctx->auth = auth;
 332         ctx->enc = enc;
 333         ctx->null = null;
 334
 335         crypto_aead_set_reqsize(
 336                 tfm,
 337                 sizeof(struct authenc_request_ctx) +
 338                 ictx->reqoff +
 339                 max_t(unsigned int,
 340                       crypto_ahash_reqsize(auth) +
 341                       sizeof(struct ahash_request),
 342                       sizeof(struct skcipher_request) +
 343                       crypto_skcipher_reqsize(enc)));
 344
 345         return 0;
 346
 347 err_free_skcipher:
 348         crypto_free_skcipher(enc);
 349 err_free_ahash:
 350         crypto_free_ahash(auth);
 351         return err;
 352 }
 353
 354 static void crypto_authenc_exit_tfm(struct crypto_aead *tfm)
 355 {
 356         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
 357
 358         crypto_free_ahash(ctx->auth);
 359         crypto_free_skcipher(ctx->enc);
 360         crypto_put_default_null_skcipher();
 361 }
 362
 363 static void crypto_authenc_free(struct aead_instance *inst)
 364 {
 365         struct authenc_instance_ctx *ctx = aead_instance_ctx(inst);
 366
 367         crypto_drop_skcipher(&ctx->enc);
 368         crypto_drop_ahash(&ctx->auth);
 369         kfree(inst);
 370 }
 371
 372 static int crypto_authenc_create(struct crypto_template *tmpl,
 373                                  struct rtattr **tb)
 374 {
 375         u32 mask;
 376         struct aead_instance *inst;
 377         struct authenc_instance_ctx *ctx;
 378         struct hash_alg_common *auth;
 379         struct crypto_alg *auth_base;
 380         struct skcipher_alg *enc;
 381         int err;
 382
 383         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD, &mask);
 384         if (err)
 385                 return err;
 386
 387         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 388         if (!inst)
 389                 return -ENOMEM;
 390         ctx = aead_instance_ctx(inst);
 391
 392         err = crypto_grab_ahash(&ctx->auth, aead_crypto_instance(inst),
 393                                 crypto_attr_alg_name(tb[1]), 0, mask);
 394         if (err)
 395                 goto err_free_inst;
 396         auth = crypto_spawn_ahash_alg(&ctx->auth);
 397         auth_base = &auth->base;
 398
 399         err = crypto_grab_skcipher(&ctx->enc, aead_crypto_instance(inst),
 400                                    crypto_attr_alg_name(tb[2]), 0, mask);
 401         if (err)
 402                 goto err_free_inst;
 403         enc = crypto_spawn_skcipher_alg(&ctx->enc);
 404
 405         ctx->reqoff = ALIGN(2 * auth->digestsize + auth_base->cra_alignmask,
 406                             auth_base->cra_alignmask + 1);
 407
 408         err = -ENAMETOOLONG;
 409         if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 410                      "authenc(%s,%s)", auth_base->cra_name,
 411                      enc->base.cra_name) >=
 412             CRYPTO_MAX_ALG_NAME)
 413                 goto err_free_inst;
 414
 415         if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 416                      "authenc(%s,%s)", auth_base->cra_driver_name,
 417                      enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 418                 goto err_free_inst;
 419
 420         inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
 421                                       auth_base->cra_priority;
 422         inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
 423         inst->alg.base.cra_alignmask = auth_base->cra_alignmask |
 424                                        enc->base.cra_alignmask;
 425         inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
 426
 427         inst->alg.ivsize = crypto_skcipher_alg_ivsize(enc);
 428         inst->alg.chunksize = crypto_skcipher_alg_chunksize(enc);
 429         inst->alg.maxauthsize = auth->digestsize;
 430
 431         inst->alg.init = crypto_authenc_init_tfm;
 432         inst->alg.exit = crypto_authenc_exit_tfm;
 433
 434         inst->alg.setkey = crypto_authenc_setkey;
 435         inst->alg.encrypt = crypto_authenc_encrypt;
 436         inst->alg.decrypt = crypto_authenc_decrypt;
 437
 438         inst->free = crypto_authenc_free;
 439
 440         err = aead_register_instance(tmpl, inst);
 441         if (err) {
 442 err_free_inst:
 443                 crypto_authenc_free(inst);
 444         }
 445         return err;
 446 }
 447
 448 static struct crypto_template crypto_authenc_tmpl = {
 449         .name = "authenc",
 450         .create = crypto_authenc_create,
 451         .module = THIS_MODULE,
 452 };
 453
 454 static int __init crypto_authenc_module_init(void)
 455 {
 456         return crypto_register_template(&crypto_authenc_tmpl);
 457 }
 458
 459 static void __exit crypto_authenc_module_exit(void)
 460 {
 461         crypto_unregister_template(&crypto_authenc_tmpl);
 462 }
 463
 464 subsys_initcall(crypto_authenc_module_init);
 465 module_exit(crypto_authenc_module_exit);
 466
 467 MODULE_LICENSE("GPL");
 468 MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");
 469 MODULE_ALIAS_CRYPTO("authenc");