crypto/authencesn.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * authencesn.c - AEAD wrapper for IPsec with extended sequence numbers,
   4  *                 derived from authenc.c
   5  *
   6  * Copyright (C) 2010 secunet Security Networks AG
   7  * Copyright (C) 2010 Steffen Klassert <steffen.klassert@secunet.com>
   8  * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
   9  */
  10
  11 #include <crypto/internal/aead.h>
  12 #include <crypto/internal/hash.h>
  13 #include <crypto/internal/skcipher.h>
  14 #include <crypto/authenc.h>
  15 #include <crypto/null.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_esn_instance_ctx {
  26         struct crypto_ahash_spawn auth;
  27         struct crypto_skcipher_spawn enc;
  28 };
  29
  30 struct crypto_authenc_esn_ctx {
  31         unsigned int reqoff;
  32         struct crypto_ahash *auth;
  33         struct crypto_skcipher *enc;
  34         struct crypto_sync_skcipher *null;
  35 };
  36
  37 struct authenc_esn_request_ctx {
  38         struct scatterlist src[2];
  39         struct scatterlist dst[2];
  40         char tail[];
  41 };
  42
  43 static void authenc_esn_request_complete(struct aead_request *req, int err)
  44 {
  45         if (err != -EINPROGRESS)
  46                 aead_request_complete(req, err);
  47 }
  48
  49 static int crypto_authenc_esn_setauthsize(struct crypto_aead *authenc_esn,
  50                                           unsigned int authsize)
  51 {
  52         if (authsize > 0 && authsize < 4)
  53                 return -EINVAL;
  54
  55         return 0;
  56 }
  57
  58 static int crypto_authenc_esn_setkey(struct crypto_aead *authenc_esn, const u8 *key,
  59                                      unsigned int keylen)
  60 {
  61         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
  62         struct crypto_ahash *auth = ctx->auth;
  63         struct crypto_skcipher *enc = ctx->enc;
  64         struct crypto_authenc_keys keys;
  65         int err = -EINVAL;
  66
  67         if (crypto_authenc_extractkeys(&keys, key, keylen) != 0)
  68                 goto out;
  69
  70         crypto_ahash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
  71         crypto_ahash_set_flags(auth, crypto_aead_get_flags(authenc_esn) &
  72                                      CRYPTO_TFM_REQ_MASK);
  73         err = crypto_ahash_setkey(auth, keys.authkey, keys.authkeylen);
  74         if (err)
  75                 goto out;
  76
  77         crypto_skcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
  78         crypto_skcipher_set_flags(enc, crypto_aead_get_flags(authenc_esn) &
  79                                          CRYPTO_TFM_REQ_MASK);
  80         err = crypto_skcipher_setkey(enc, keys.enckey, keys.enckeylen);
  81 out:
  82         memzero_explicit(&keys, sizeof(keys));
  83         return err;
  84 }
  85
  86 static int crypto_authenc_esn_genicv_tail(struct aead_request *req,
  87                                           unsigned int flags)
  88 {
  89         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
  90         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
  91         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
  92         struct crypto_ahash *auth = ctx->auth;
  93         u8 *hash = PTR_ALIGN((u8 *)areq_ctx->tail,
  94                              crypto_ahash_alignmask(auth) + 1);
  95         unsigned int authsize = crypto_aead_authsize(authenc_esn);
  96         unsigned int assoclen = req->assoclen;
  97         unsigned int cryptlen = req->cryptlen;
  98         struct scatterlist *dst = req->dst;
  99         u32 tmp[2];
 100
 101         /* Move high-order bits of sequence number back. */
 102         scatterwalk_map_and_copy(tmp, dst, 4, 4, 0);
 103         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 0);
 104         scatterwalk_map_and_copy(tmp, dst, 0, 8, 1);
 105
 106         scatterwalk_map_and_copy(hash, dst, assoclen + cryptlen, authsize, 1);
 107         return 0;
 108 }
 109
 110 static void authenc_esn_geniv_ahash_done(void *data, int err)
 111 {
 112         struct aead_request *req = data;
 113
 114         err = err ?: crypto_authenc_esn_genicv_tail(req, 0);
 115         aead_request_complete(req, err);
 116 }
 117
 118 static int crypto_authenc_esn_genicv(struct aead_request *req,
 119                                      unsigned int flags)
 120 {
 121         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 122         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 123         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 124         struct crypto_ahash *auth = ctx->auth;
 125         u8 *hash = PTR_ALIGN((u8 *)areq_ctx->tail,
 126                              crypto_ahash_alignmask(auth) + 1);
 127         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
 128         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 129         unsigned int assoclen = req->assoclen;
 130         unsigned int cryptlen = req->cryptlen;
 131         struct scatterlist *dst = req->dst;
 132         u32 tmp[2];
 133
 134         if (!authsize)
 135                 return 0;
 136
 137         /* Move high-order bits of sequence number to the end. */
 138         scatterwalk_map_and_copy(tmp, dst, 0, 8, 0);
 139         scatterwalk_map_and_copy(tmp, dst, 4, 4, 1);
 140         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 1);
 141
 142         sg_init_table(areq_ctx->dst, 2);
 143         dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
 144
 145         ahash_request_set_tfm(ahreq, auth);
 146         ahash_request_set_crypt(ahreq, dst, hash, assoclen + cryptlen);
 147         ahash_request_set_callback(ahreq, flags,
 148                                    authenc_esn_geniv_ahash_done, req);
 149
 150         return crypto_ahash_digest(ahreq) ?:
 151                crypto_authenc_esn_genicv_tail(req, aead_request_flags(req));
 152 }
 153
 154
 155 static void crypto_authenc_esn_encrypt_done(void *data, int err)
 156 {
 157         struct aead_request *areq = data;
 158
 159         if (!err)
 160                 err = crypto_authenc_esn_genicv(areq, 0);
 161
 162         authenc_esn_request_complete(areq, err);
 163 }
 164
 165 static int crypto_authenc_esn_copy(struct aead_request *req, unsigned int len)
 166 {
 167         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 168         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 169         SYNC_SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);
 170
 171         skcipher_request_set_sync_tfm(skreq, ctx->null);
 172         skcipher_request_set_callback(skreq, aead_request_flags(req),
 173                                       NULL, NULL);
 174         skcipher_request_set_crypt(skreq, req->src, req->dst, len, NULL);
 175
 176         return crypto_skcipher_encrypt(skreq);
 177 }
 178
 179 static int crypto_authenc_esn_encrypt(struct aead_request *req)
 180 {
 181         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 182         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 183         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 184         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 185                                                   ctx->reqoff);
 186         struct crypto_skcipher *enc = ctx->enc;
 187         unsigned int assoclen = req->assoclen;
 188         unsigned int cryptlen = req->cryptlen;
 189         struct scatterlist *src, *dst;
 190         int err;
 191
 192         sg_init_table(areq_ctx->src, 2);
 193         src = scatterwalk_ffwd(areq_ctx->src, req->src, assoclen);
 194         dst = src;
 195
 196         if (req->src != req->dst) {
 197                 err = crypto_authenc_esn_copy(req, assoclen);
 198                 if (err)
 199                         return err;
 200
 201                 sg_init_table(areq_ctx->dst, 2);
 202                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, assoclen);
 203         }
 204
 205         skcipher_request_set_tfm(skreq, enc);
 206         skcipher_request_set_callback(skreq, aead_request_flags(req),
 207                                       crypto_authenc_esn_encrypt_done, req);
 208         skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
 209
 210         err = crypto_skcipher_encrypt(skreq);
 211         if (err)
 212                 return err;
 213
 214         return crypto_authenc_esn_genicv(req, aead_request_flags(req));
 215 }
 216
 217 static int crypto_authenc_esn_decrypt_tail(struct aead_request *req,
 218                                            unsigned int flags)
 219 {
 220         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 221         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 222         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 223         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 224         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 225                                                   ctx->reqoff);
 226         struct crypto_ahash *auth = ctx->auth;
 227         u8 *ohash = PTR_ALIGN((u8 *)areq_ctx->tail,
 228                               crypto_ahash_alignmask(auth) + 1);
 229         unsigned int cryptlen = req->cryptlen - authsize;
 230         unsigned int assoclen = req->assoclen;
 231         struct scatterlist *dst = req->dst;
 232         u8 *ihash = ohash + crypto_ahash_digestsize(auth);
 233         u32 tmp[2];
 234
 235         if (!authsize)
 236                 goto decrypt;
 237
 238         /* Move high-order bits of sequence number back. */
 239         scatterwalk_map_and_copy(tmp, dst, 4, 4, 0);
 240         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 0);
 241         scatterwalk_map_and_copy(tmp, dst, 0, 8, 1);
 242
 243         if (crypto_memneq(ihash, ohash, authsize))
 244                 return -EBADMSG;
 245
 246 decrypt:
 247
 248         sg_init_table(areq_ctx->dst, 2);
 249         dst = scatterwalk_ffwd(areq_ctx->dst, dst, 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, dst, dst, cryptlen, req->iv);
 255
 256         return crypto_skcipher_decrypt(skreq);
 257 }
 258
 259 static void authenc_esn_verify_ahash_done(void *data, int err)
 260 {
 261         struct aead_request *req = data;
 262
 263         err = err ?: crypto_authenc_esn_decrypt_tail(req, 0);
 264         authenc_esn_request_complete(req, err);
 265 }
 266
 267 static int crypto_authenc_esn_decrypt(struct aead_request *req)
 268 {
 269         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 270         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 271         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 272         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
 273         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 274         struct crypto_ahash *auth = ctx->auth;
 275         u8 *ohash = PTR_ALIGN((u8 *)areq_ctx->tail,
 276                               crypto_ahash_alignmask(auth) + 1);
 277         unsigned int assoclen = req->assoclen;
 278         unsigned int cryptlen = req->cryptlen;
 279         u8 *ihash = ohash + crypto_ahash_digestsize(auth);
 280         struct scatterlist *dst = req->dst;
 281         u32 tmp[2];
 282         int err;
 283
 284         cryptlen -= authsize;
 285
 286         if (req->src != dst) {
 287                 err = crypto_authenc_esn_copy(req, assoclen + cryptlen);
 288                 if (err)
 289                         return err;
 290         }
 291
 292         scatterwalk_map_and_copy(ihash, req->src, assoclen + cryptlen,
 293                                  authsize, 0);
 294
 295         if (!authsize)
 296                 goto tail;
 297
 298         /* Move high-order bits of sequence number to the end. */
 299         scatterwalk_map_and_copy(tmp, dst, 0, 8, 0);
 300         scatterwalk_map_and_copy(tmp, dst, 4, 4, 1);
 301         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 1);
 302
 303         sg_init_table(areq_ctx->dst, 2);
 304         dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
 305
 306         ahash_request_set_tfm(ahreq, auth);
 307         ahash_request_set_crypt(ahreq, dst, ohash, assoclen + cryptlen);
 308         ahash_request_set_callback(ahreq, aead_request_flags(req),
 309                                    authenc_esn_verify_ahash_done, req);
 310
 311         err = crypto_ahash_digest(ahreq);
 312         if (err)
 313                 return err;
 314
 315 tail:
 316         return crypto_authenc_esn_decrypt_tail(req, aead_request_flags(req));
 317 }
 318
 319 static int crypto_authenc_esn_init_tfm(struct crypto_aead *tfm)
 320 {
 321         struct aead_instance *inst = aead_alg_instance(tfm);
 322         struct authenc_esn_instance_ctx *ictx = aead_instance_ctx(inst);
 323         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(tfm);
 324         struct crypto_ahash *auth;
 325         struct crypto_skcipher *enc;
 326         struct crypto_sync_skcipher *null;
 327         int err;
 328
 329         auth = crypto_spawn_ahash(&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_ahash;
 337
 338         null = crypto_get_default_null_skcipher();
 339         err = PTR_ERR(null);
 340         if (IS_ERR(null))
 341                 goto err_free_skcipher;
 342
 343         ctx->auth = auth;
 344         ctx->enc = enc;
 345         ctx->null = null;
 346
 347         ctx->reqoff = ALIGN(2 * crypto_ahash_digestsize(auth),
 348                             crypto_ahash_alignmask(auth) + 1);
 349
 350         crypto_aead_set_reqsize(
 351                 tfm,
 352                 sizeof(struct authenc_esn_request_ctx) +
 353                 ctx->reqoff +
 354                 max_t(unsigned int,
 355                       crypto_ahash_reqsize(auth) +
 356                       sizeof(struct ahash_request),
 357                       sizeof(struct skcipher_request) +
 358                       crypto_skcipher_reqsize(enc)));
 359
 360         return 0;
 361
 362 err_free_skcipher:
 363         crypto_free_skcipher(enc);
 364 err_free_ahash:
 365         crypto_free_ahash(auth);
 366         return err;
 367 }
 368
 369 static void crypto_authenc_esn_exit_tfm(struct crypto_aead *tfm)
 370 {
 371         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(tfm);
 372
 373         crypto_free_ahash(ctx->auth);
 374         crypto_free_skcipher(ctx->enc);
 375         crypto_put_default_null_skcipher();
 376 }
 377
 378 static void crypto_authenc_esn_free(struct aead_instance *inst)
 379 {
 380         struct authenc_esn_instance_ctx *ctx = aead_instance_ctx(inst);
 381
 382         crypto_drop_skcipher(&ctx->enc);
 383         crypto_drop_ahash(&ctx->auth);
 384         kfree(inst);
 385 }
 386
 387 static int crypto_authenc_esn_create(struct crypto_template *tmpl,
 388                                      struct rtattr **tb)
 389 {
 390         u32 mask;
 391         struct aead_instance *inst;
 392         struct authenc_esn_instance_ctx *ctx;
 393         struct hash_alg_common *auth;
 394         struct crypto_alg *auth_base;
 395         struct skcipher_alg *enc;
 396         int err;
 397
 398         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD, &mask);
 399         if (err)
 400                 return err;
 401
 402         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 403         if (!inst)
 404                 return -ENOMEM;
 405         ctx = aead_instance_ctx(inst);
 406
 407         err = crypto_grab_ahash(&ctx->auth, aead_crypto_instance(inst),
 408                                 crypto_attr_alg_name(tb[1]), 0, mask);
 409         if (err)
 410                 goto err_free_inst;
 411         auth = crypto_spawn_ahash_alg(&ctx->auth);
 412         auth_base = &auth->base;
 413
 414         err = crypto_grab_skcipher(&ctx->enc, aead_crypto_instance(inst),
 415                                    crypto_attr_alg_name(tb[2]), 0, mask);
 416         if (err)
 417                 goto err_free_inst;
 418         enc = crypto_spawn_skcipher_alg(&ctx->enc);
 419
 420         err = -ENAMETOOLONG;
 421         if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 422                      "authencesn(%s,%s)", auth_base->cra_name,
 423                      enc->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
 424                 goto err_free_inst;
 425
 426         if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 427                      "authencesn(%s,%s)", auth_base->cra_driver_name,
 428                      enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 429                 goto err_free_inst;
 430
 431         inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
 432                                       auth_base->cra_priority;
 433         inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
 434         inst->alg.base.cra_alignmask = auth_base->cra_alignmask |
 435                                        enc->base.cra_alignmask;
 436         inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_esn_ctx);
 437
 438         inst->alg.ivsize = crypto_skcipher_alg_ivsize(enc);
 439         inst->alg.chunksize = crypto_skcipher_alg_chunksize(enc);
 440         inst->alg.maxauthsize = auth->digestsize;
 441
 442         inst->alg.init = crypto_authenc_esn_init_tfm;
 443         inst->alg.exit = crypto_authenc_esn_exit_tfm;
 444
 445         inst->alg.setkey = crypto_authenc_esn_setkey;
 446         inst->alg.setauthsize = crypto_authenc_esn_setauthsize;
 447         inst->alg.encrypt = crypto_authenc_esn_encrypt;
 448         inst->alg.decrypt = crypto_authenc_esn_decrypt;
 449
 450         inst->free = crypto_authenc_esn_free;
 451
 452         err = aead_register_instance(tmpl, inst);
 453         if (err) {
 454 err_free_inst:
 455                 crypto_authenc_esn_free(inst);
 456         }
 457         return err;
 458 }
 459
 460 static struct crypto_template crypto_authenc_esn_tmpl = {
 461         .name = "authencesn",
 462         .create = crypto_authenc_esn_create,
 463         .module = THIS_MODULE,
 464 };
 465
 466 static int __init crypto_authenc_esn_module_init(void)
 467 {
 468         return crypto_register_template(&crypto_authenc_esn_tmpl);
 469 }
 470
 471 static void __exit crypto_authenc_esn_module_exit(void)
 472 {
 473         crypto_unregister_template(&crypto_authenc_esn_tmpl);
 474 }
 475
 476 subsys_initcall(crypto_authenc_esn_module_init);
 477 module_exit(crypto_authenc_esn_module_exit);
 478
 479 MODULE_LICENSE("GPL");
 480 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
 481 MODULE_DESCRIPTION("AEAD wrapper for IPsec with extended sequence numbers");
 482 MODULE_ALIAS_CRYPTO("authencesn");