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 authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
  91         u8 *hash = areq_ctx->tail;
  92         unsigned int authsize = crypto_aead_authsize(authenc_esn);
  93         unsigned int assoclen = req->assoclen;
  94         unsigned int cryptlen = req->cryptlen;
  95         struct scatterlist *dst = req->dst;
  96         u32 tmp[2];
  97
  98         /* Move high-order bits of sequence number back. */
  99         scatterwalk_map_and_copy(tmp, dst, 4, 4, 0);
 100         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 0);
 101         scatterwalk_map_and_copy(tmp, dst, 0, 8, 1);
 102
 103         scatterwalk_map_and_copy(hash, dst, assoclen + cryptlen, authsize, 1);
 104         return 0;
 105 }
 106
 107 static void authenc_esn_geniv_ahash_done(void *data, int err)
 108 {
 109         struct aead_request *req = data;
 110
 111         err = err ?: crypto_authenc_esn_genicv_tail(req, 0);
 112         aead_request_complete(req, err);
 113 }
 114
 115 static int crypto_authenc_esn_genicv(struct aead_request *req,
 116                                      unsigned int flags)
 117 {
 118         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 119         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 120         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 121         struct crypto_ahash *auth = ctx->auth;
 122         u8 *hash = areq_ctx->tail;
 123         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
 124         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 125         unsigned int assoclen = req->assoclen;
 126         unsigned int cryptlen = req->cryptlen;
 127         struct scatterlist *dst = req->dst;
 128         u32 tmp[2];
 129
 130         if (!authsize)
 131                 return 0;
 132
 133         /* Move high-order bits of sequence number to the end. */
 134         scatterwalk_map_and_copy(tmp, dst, 0, 8, 0);
 135         scatterwalk_map_and_copy(tmp, dst, 4, 4, 1);
 136         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 1);
 137
 138         sg_init_table(areq_ctx->dst, 2);
 139         dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
 140
 141         ahash_request_set_tfm(ahreq, auth);
 142         ahash_request_set_crypt(ahreq, dst, hash, assoclen + cryptlen);
 143         ahash_request_set_callback(ahreq, flags,
 144                                    authenc_esn_geniv_ahash_done, req);
 145
 146         return crypto_ahash_digest(ahreq) ?:
 147                crypto_authenc_esn_genicv_tail(req, aead_request_flags(req));
 148 }
 149
 150
 151 static void crypto_authenc_esn_encrypt_done(void *data, int err)
 152 {
 153         struct aead_request *areq = data;
 154
 155         if (!err)
 156                 err = crypto_authenc_esn_genicv(areq, 0);
 157
 158         authenc_esn_request_complete(areq, err);
 159 }
 160
 161 static int crypto_authenc_esn_copy(struct aead_request *req, unsigned int len)
 162 {
 163         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 164         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 165         SYNC_SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);
 166
 167         skcipher_request_set_sync_tfm(skreq, ctx->null);
 168         skcipher_request_set_callback(skreq, aead_request_flags(req),
 169                                       NULL, NULL);
 170         skcipher_request_set_crypt(skreq, req->src, req->dst, len, NULL);
 171
 172         return crypto_skcipher_encrypt(skreq);
 173 }
 174
 175 static int crypto_authenc_esn_encrypt(struct aead_request *req)
 176 {
 177         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 178         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 179         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 180         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 181                                                   ctx->reqoff);
 182         struct crypto_skcipher *enc = ctx->enc;
 183         unsigned int assoclen = req->assoclen;
 184         unsigned int cryptlen = req->cryptlen;
 185         struct scatterlist *src, *dst;
 186         int err;
 187
 188         sg_init_table(areq_ctx->src, 2);
 189         src = scatterwalk_ffwd(areq_ctx->src, req->src, assoclen);
 190         dst = src;
 191
 192         if (req->src != req->dst) {
 193                 err = crypto_authenc_esn_copy(req, assoclen);
 194                 if (err)
 195                         return err;
 196
 197                 sg_init_table(areq_ctx->dst, 2);
 198                 dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, assoclen);
 199         }
 200
 201         skcipher_request_set_tfm(skreq, enc);
 202         skcipher_request_set_callback(skreq, aead_request_flags(req),
 203                                       crypto_authenc_esn_encrypt_done, req);
 204         skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
 205
 206         err = crypto_skcipher_encrypt(skreq);
 207         if (err)
 208                 return err;
 209
 210         return crypto_authenc_esn_genicv(req, aead_request_flags(req));
 211 }
 212
 213 static int crypto_authenc_esn_decrypt_tail(struct aead_request *req,
 214                                            unsigned int flags)
 215 {
 216         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 217         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 218         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 219         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 220         struct skcipher_request *skreq = (void *)(areq_ctx->tail +
 221                                                   ctx->reqoff);
 222         struct crypto_ahash *auth = ctx->auth;
 223         u8 *ohash = areq_ctx->tail;
 224         unsigned int cryptlen = req->cryptlen - authsize;
 225         unsigned int assoclen = req->assoclen;
 226         struct scatterlist *dst = req->dst;
 227         u8 *ihash = ohash + crypto_ahash_digestsize(auth);
 228         u32 tmp[2];
 229
 230         if (!authsize)
 231                 goto decrypt;
 232
 233         /* Move high-order bits of sequence number back. */
 234         scatterwalk_map_and_copy(tmp, dst, 4, 4, 0);
 235         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 0);
 236         scatterwalk_map_and_copy(tmp, dst, 0, 8, 1);
 237
 238         if (crypto_memneq(ihash, ohash, authsize))
 239                 return -EBADMSG;
 240
 241 decrypt:
 242
 243         sg_init_table(areq_ctx->dst, 2);
 244         dst = scatterwalk_ffwd(areq_ctx->dst, dst, assoclen);
 245
 246         skcipher_request_set_tfm(skreq, ctx->enc);
 247         skcipher_request_set_callback(skreq, flags,
 248                                       req->base.complete, req->base.data);
 249         skcipher_request_set_crypt(skreq, dst, dst, cryptlen, req->iv);
 250
 251         return crypto_skcipher_decrypt(skreq);
 252 }
 253
 254 static void authenc_esn_verify_ahash_done(void *data, int err)
 255 {
 256         struct aead_request *req = data;
 257
 258         err = err ?: crypto_authenc_esn_decrypt_tail(req, 0);
 259         authenc_esn_request_complete(req, err);
 260 }
 261
 262 static int crypto_authenc_esn_decrypt(struct aead_request *req)
 263 {
 264         struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 265         struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 266         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
 267         struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
 268         unsigned int authsize = crypto_aead_authsize(authenc_esn);
 269         struct crypto_ahash *auth = ctx->auth;
 270         u8 *ohash = areq_ctx->tail;
 271         unsigned int assoclen = req->assoclen;
 272         unsigned int cryptlen = req->cryptlen;
 273         u8 *ihash = ohash + crypto_ahash_digestsize(auth);
 274         struct scatterlist *dst = req->dst;
 275         u32 tmp[2];
 276         int err;
 277
 278         cryptlen -= authsize;
 279
 280         if (req->src != dst) {
 281                 err = crypto_authenc_esn_copy(req, assoclen + cryptlen);
 282                 if (err)
 283                         return err;
 284         }
 285
 286         scatterwalk_map_and_copy(ihash, req->src, assoclen + cryptlen,
 287                                  authsize, 0);
 288
 289         if (!authsize)
 290                 goto tail;
 291
 292         /* Move high-order bits of sequence number to the end. */
 293         scatterwalk_map_and_copy(tmp, dst, 0, 8, 0);
 294         scatterwalk_map_and_copy(tmp, dst, 4, 4, 1);
 295         scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 1);
 296
 297         sg_init_table(areq_ctx->dst, 2);
 298         dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
 299
 300         ahash_request_set_tfm(ahreq, auth);
 301         ahash_request_set_crypt(ahreq, dst, ohash, assoclen + cryptlen);
 302         ahash_request_set_callback(ahreq, aead_request_flags(req),
 303                                    authenc_esn_verify_ahash_done, req);
 304
 305         err = crypto_ahash_digest(ahreq);
 306         if (err)
 307                 return err;
 308
 309 tail:
 310         return crypto_authenc_esn_decrypt_tail(req, aead_request_flags(req));
 311 }
 312
 313 static int crypto_authenc_esn_init_tfm(struct crypto_aead *tfm)
 314 {
 315         struct aead_instance *inst = aead_alg_instance(tfm);
 316         struct authenc_esn_instance_ctx *ictx = aead_instance_ctx(inst);
 317         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(tfm);
 318         struct crypto_ahash *auth;
 319         struct crypto_skcipher *enc;
 320         struct crypto_sync_skcipher *null;
 321         int err;
 322
 323         auth = crypto_spawn_ahash(&ictx->auth);
 324         if (IS_ERR(auth))
 325                 return PTR_ERR(auth);
 326
 327         enc = crypto_spawn_skcipher(&ictx->enc);
 328         err = PTR_ERR(enc);
 329         if (IS_ERR(enc))
 330                 goto err_free_ahash;
 331
 332         null = crypto_get_default_null_skcipher();
 333         err = PTR_ERR(null);
 334         if (IS_ERR(null))
 335                 goto err_free_skcipher;
 336
 337         ctx->auth = auth;
 338         ctx->enc = enc;
 339         ctx->null = null;
 340
 341         ctx->reqoff = 2 * crypto_ahash_digestsize(auth);
 342
 343         crypto_aead_set_reqsize(
 344                 tfm,
 345                 sizeof(struct authenc_esn_request_ctx) +
 346                 ctx->reqoff +
 347                 max_t(unsigned int,
 348                       crypto_ahash_reqsize(auth) +
 349                       sizeof(struct ahash_request),
 350                       sizeof(struct skcipher_request) +
 351                       crypto_skcipher_reqsize(enc)));
 352
 353         return 0;
 354
 355 err_free_skcipher:
 356         crypto_free_skcipher(enc);
 357 err_free_ahash:
 358         crypto_free_ahash(auth);
 359         return err;
 360 }
 361
 362 static void crypto_authenc_esn_exit_tfm(struct crypto_aead *tfm)
 363 {
 364         struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(tfm);
 365
 366         crypto_free_ahash(ctx->auth);
 367         crypto_free_skcipher(ctx->enc);
 368         crypto_put_default_null_skcipher();
 369 }
 370
 371 static void crypto_authenc_esn_free(struct aead_instance *inst)
 372 {
 373         struct authenc_esn_instance_ctx *ctx = aead_instance_ctx(inst);
 374
 375         crypto_drop_skcipher(&ctx->enc);
 376         crypto_drop_ahash(&ctx->auth);
 377         kfree(inst);
 378 }
 379
 380 static int crypto_authenc_esn_create(struct crypto_template *tmpl,
 381                                      struct rtattr **tb)
 382 {
 383         u32 mask;
 384         struct aead_instance *inst;
 385         struct authenc_esn_instance_ctx *ctx;
 386         struct skcipher_alg_common *enc;
 387         struct hash_alg_common *auth;
 388         struct crypto_alg *auth_base;
 389         int err;
 390
 391         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD, &mask);
 392         if (err)
 393                 return err;
 394
 395         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 396         if (!inst)
 397                 return -ENOMEM;
 398         ctx = aead_instance_ctx(inst);
 399
 400         err = crypto_grab_ahash(&ctx->auth, aead_crypto_instance(inst),
 401                                 crypto_attr_alg_name(tb[1]), 0, mask);
 402         if (err)
 403                 goto err_free_inst;
 404         auth = crypto_spawn_ahash_alg(&ctx->auth);
 405         auth_base = &auth->base;
 406
 407         err = crypto_grab_skcipher(&ctx->enc, aead_crypto_instance(inst),
 408                                    crypto_attr_alg_name(tb[2]), 0, mask);
 409         if (err)
 410                 goto err_free_inst;
 411         enc = crypto_spawn_skcipher_alg_common(&ctx->enc);
 412
 413         err = -ENAMETOOLONG;
 414         if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 415                      "authencesn(%s,%s)", auth_base->cra_name,
 416                      enc->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
 417                 goto err_free_inst;
 418
 419         if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 420                      "authencesn(%s,%s)", auth_base->cra_driver_name,
 421                      enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 422                 goto err_free_inst;
 423
 424         inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
 425                                       auth_base->cra_priority;
 426         inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
 427         inst->alg.base.cra_alignmask = enc->base.cra_alignmask;
 428         inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_esn_ctx);
 429
 430         inst->alg.ivsize = enc->ivsize;
 431         inst->alg.chunksize = enc->chunksize;
 432         inst->alg.maxauthsize = auth->digestsize;
 433
 434         inst->alg.init = crypto_authenc_esn_init_tfm;
 435         inst->alg.exit = crypto_authenc_esn_exit_tfm;
 436
 437         inst->alg.setkey = crypto_authenc_esn_setkey;
 438         inst->alg.setauthsize = crypto_authenc_esn_setauthsize;
 439         inst->alg.encrypt = crypto_authenc_esn_encrypt;
 440         inst->alg.decrypt = crypto_authenc_esn_decrypt;
 441
 442         inst->free = crypto_authenc_esn_free;
 443
 444         err = aead_register_instance(tmpl, inst);
 445         if (err) {
 446 err_free_inst:
 447                 crypto_authenc_esn_free(inst);
 448         }
 449         return err;
 450 }
 451
 452 static struct crypto_template crypto_authenc_esn_tmpl = {
 453         .name = "authencesn",
 454         .create = crypto_authenc_esn_create,
 455         .module = THIS_MODULE,
 456 };
 457
 458 static int __init crypto_authenc_esn_module_init(void)
 459 {
 460         return crypto_register_template(&crypto_authenc_esn_tmpl);
 461 }
 462
 463 static void __exit crypto_authenc_esn_module_exit(void)
 464 {
 465         crypto_unregister_template(&crypto_authenc_esn_tmpl);
 466 }
 467
 468 subsys_initcall(crypto_authenc_esn_module_init);
 469 module_exit(crypto_authenc_esn_module_exit);
 470
 471 MODULE_LICENSE("GPL");
 472 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
 473 MODULE_DESCRIPTION("AEAD wrapper for IPsec with extended sequence numbers");
 474 MODULE_ALIAS_CRYPTO("authencesn");