crypto/authenc.c

   1 /*
   2  * Authenc: Simple AEAD wrapper for IPsec
   3  *
   4  * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the Free
   8  * Software Foundation; either version 2 of the License, or (at your option)
   9  * any later version.
  10  *
  11  */
  12
  13 #include <crypto/internal/skcipher.h>
  14 #include <crypto/authenc.h>
  15 #include <crypto/scatterwalk.h>
  16 #include <linux/err.h>
  17 #include <linux/init.h>
  18 #include <linux/kernel.h>
  19 #include <linux/module.h>
  20 #include <linux/rtnetlink.h>
  21 #include <linux/slab.h>
  22 #include <linux/spinlock.h>
  23
  24 struct authenc_instance_ctx {
  25         struct crypto_spawn auth;
  26         struct crypto_skcipher_spawn enc;
  27 };
  28
  29 struct crypto_authenc_ctx {
  30         spinlock_t auth_lock;
  31         struct crypto_hash *auth;
  32         struct crypto_ablkcipher *enc;
  33 };
  34
  35 static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
  36                                  unsigned int keylen)
  37 {
  38         unsigned int authkeylen;
  39         unsigned int enckeylen;
  40         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  41         struct crypto_hash *auth = ctx->auth;
  42         struct crypto_ablkcipher *enc = ctx->enc;
  43         struct rtattr *rta = (void *)key;
  44         struct crypto_authenc_key_param *param;
  45         int err = -EINVAL;
  46
  47         if (!RTA_OK(rta, keylen))
  48                 goto badkey;
  49         if (rta->rta_type != CRYPTO_AUTHENC_KEYA_PARAM)
  50                 goto badkey;
  51         if (RTA_PAYLOAD(rta) < sizeof(*param))
  52                 goto badkey;
  53
  54         param = RTA_DATA(rta);
  55         enckeylen = be32_to_cpu(param->enckeylen);
  56
  57         key += RTA_ALIGN(rta->rta_len);
  58         keylen -= RTA_ALIGN(rta->rta_len);
  59
  60         if (keylen < enckeylen)
  61                 goto badkey;
  62
  63         authkeylen = keylen - enckeylen;
  64
  65         crypto_hash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
  66         crypto_hash_set_flags(auth, crypto_aead_get_flags(authenc) &
  67                                     CRYPTO_TFM_REQ_MASK);
  68         err = crypto_hash_setkey(auth, key, authkeylen);
  69         crypto_aead_set_flags(authenc, crypto_hash_get_flags(auth) &
  70                                        CRYPTO_TFM_RES_MASK);
  71
  72         if (err)
  73                 goto out;
  74
  75         crypto_ablkcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
  76         crypto_ablkcipher_set_flags(enc, crypto_aead_get_flags(authenc) &
  77                                          CRYPTO_TFM_REQ_MASK);
  78         err = crypto_ablkcipher_setkey(enc, key + authkeylen, enckeylen);
  79         crypto_aead_set_flags(authenc, crypto_ablkcipher_get_flags(enc) &
  80                                        CRYPTO_TFM_RES_MASK);
  81
  82 out:
  83         return err;
  84
  85 badkey:
  86         crypto_aead_set_flags(authenc, CRYPTO_TFM_RES_BAD_KEY_LEN);
  87         goto out;
  88 }
  89
  90 static u8 *crypto_authenc_hash(struct aead_request *req, unsigned int flags,
  91                                struct scatterlist *cipher,
  92                                unsigned int cryptlen)
  93 {
  94         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
  95         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  96         struct crypto_hash *auth = ctx->auth;
  97         struct hash_desc desc = {
  98                 .tfm = auth,
  99                 .flags = aead_request_flags(req) & flags,
 100         };
 101         u8 *hash = aead_request_ctx(req);
 102         int err;
 103
 104         hash = (u8 *)ALIGN((unsigned long)hash + crypto_hash_alignmask(auth),
 105                            crypto_hash_alignmask(auth) + 1);
 106
 107         spin_lock_bh(&ctx->auth_lock);
 108         err = crypto_hash_init(&desc);
 109         if (err)
 110                 goto auth_unlock;
 111
 112         err = crypto_hash_update(&desc, req->assoc, req->assoclen);
 113         if (err)
 114                 goto auth_unlock;
 115
 116         err = crypto_hash_update(&desc, cipher, cryptlen);
 117         if (err)
 118                 goto auth_unlock;
 119
 120         err = crypto_hash_final(&desc, hash);
 121 auth_unlock:
 122         spin_unlock_bh(&ctx->auth_lock);
 123
 124         if (err)
 125                 return ERR_PTR(err);
 126
 127         return hash;
 128 }
 129
 130 static int crypto_authenc_genicv(struct aead_request *req, unsigned int flags)
 131 {
 132         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 133         struct scatterlist *dst = req->dst;
 134         unsigned int cryptlen = req->cryptlen;
 135         u8 *hash;
 136
 137         hash = crypto_authenc_hash(req, flags, dst, cryptlen);
 138         if (IS_ERR(hash))
 139                 return PTR_ERR(hash);
 140
 141         scatterwalk_map_and_copy(hash, dst, cryptlen,
 142                                  crypto_aead_authsize(authenc), 1);
 143         return 0;
 144 }
 145
 146 static void crypto_authenc_encrypt_done(struct crypto_async_request *req,
 147                                         int err)
 148 {
 149         if (!err)
 150                 err = crypto_authenc_genicv(req->data, 0);
 151
 152         aead_request_complete(req->data, err);
 153 }
 154
 155 static int crypto_authenc_encrypt(struct aead_request *req)
 156 {
 157         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 158         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 159         struct ablkcipher_request *abreq = aead_request_ctx(req);
 160         int err;
 161
 162         ablkcipher_request_set_tfm(abreq, ctx->enc);
 163         ablkcipher_request_set_callback(abreq, aead_request_flags(req),
 164                                         crypto_authenc_encrypt_done, req);
 165         ablkcipher_request_set_crypt(abreq, req->src, req->dst, req->cryptlen,
 166                                      req->iv);
 167
 168         err = crypto_ablkcipher_encrypt(abreq);
 169         if (err)
 170                 return err;
 171
 172         return crypto_authenc_genicv(req, CRYPTO_TFM_REQ_MAY_SLEEP);
 173 }
 174
 175 static int crypto_authenc_verify(struct aead_request *req,
 176                                  unsigned int cryptlen)
 177 {
 178         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 179         u8 *ohash;
 180         u8 *ihash;
 181         struct scatterlist *src = req->src;
 182         unsigned int authsize;
 183
 184         ohash = crypto_authenc_hash(req, CRYPTO_TFM_REQ_MAY_SLEEP, src,
 185                                     cryptlen);
 186         if (IS_ERR(ohash))
 187                 return PTR_ERR(ohash);
 188
 189         authsize = crypto_aead_authsize(authenc);
 190         ihash = ohash + authsize;
 191         scatterwalk_map_and_copy(ihash, src, cryptlen, authsize, 0);
 192         return memcmp(ihash, ohash, authsize) ? -EBADMSG: 0;
 193 }
 194
 195 static void crypto_authenc_decrypt_done(struct crypto_async_request *req,
 196                                         int err)
 197 {
 198         aead_request_complete(req->data, err);
 199 }
 200
 201 static int crypto_authenc_decrypt(struct aead_request *req)
 202 {
 203         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 204         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 205         struct ablkcipher_request *abreq = aead_request_ctx(req);
 206         unsigned int cryptlen = req->cryptlen;
 207         unsigned int authsize = crypto_aead_authsize(authenc);
 208         int err;
 209
 210         if (cryptlen < authsize)
 211                 return -EINVAL;
 212         cryptlen -= authsize;
 213
 214         err = crypto_authenc_verify(req, cryptlen);
 215         if (err)
 216                 return err;
 217
 218         ablkcipher_request_set_tfm(abreq, ctx->enc);
 219         ablkcipher_request_set_callback(abreq, aead_request_flags(req),
 220                                         crypto_authenc_decrypt_done, req);
 221         ablkcipher_request_set_crypt(abreq, req->src, req->dst, cryptlen,
 222                                      req->iv);
 223
 224         return crypto_ablkcipher_decrypt(abreq);
 225 }
 226
 227 static int crypto_authenc_init_tfm(struct crypto_tfm *tfm)
 228 {
 229         struct crypto_instance *inst = (void *)tfm->__crt_alg;
 230         struct authenc_instance_ctx *ictx = crypto_instance_ctx(inst);
 231         struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
 232         struct crypto_hash *auth;
 233         struct crypto_ablkcipher *enc;
 234         int err;
 235
 236         auth = crypto_spawn_hash(&ictx->auth);
 237         if (IS_ERR(auth))
 238                 return PTR_ERR(auth);
 239
 240         enc = crypto_spawn_skcipher(&ictx->enc);
 241         err = PTR_ERR(enc);
 242         if (IS_ERR(enc))
 243                 goto err_free_hash;
 244
 245         ctx->auth = auth;
 246         ctx->enc = enc;
 247         tfm->crt_aead.reqsize = max_t(unsigned int,
 248                                       (crypto_hash_alignmask(auth) &
 249                                        ~(crypto_tfm_ctx_alignment() - 1)) +
 250                                       crypto_hash_digestsize(auth) * 2,
 251                                       sizeof(struct ablkcipher_request) +
 252                                       crypto_ablkcipher_reqsize(enc));
 253
 254         spin_lock_init(&ctx->auth_lock);
 255
 256         return 0;
 257
 258 err_free_hash:
 259         crypto_free_hash(auth);
 260         return err;
 261 }
 262
 263 static void crypto_authenc_exit_tfm(struct crypto_tfm *tfm)
 264 {
 265         struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
 266
 267         crypto_free_hash(ctx->auth);
 268         crypto_free_ablkcipher(ctx->enc);
 269 }
 270
 271 static struct crypto_instance *crypto_authenc_alloc(struct rtattr **tb)
 272 {
 273         struct crypto_attr_type *algt;
 274         struct crypto_instance *inst;
 275         struct crypto_alg *auth;
 276         struct crypto_alg *enc;
 277         struct authenc_instance_ctx *ctx;
 278         const char *enc_name;
 279         int err;
 280
 281         algt = crypto_get_attr_type(tb);
 282         err = PTR_ERR(algt);
 283         if (IS_ERR(algt))
 284                 return ERR_PTR(err);
 285
 286         if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
 287                 return ERR_PTR(-EINVAL);
 288
 289         auth = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
 290                                CRYPTO_ALG_TYPE_HASH_MASK);
 291         if (IS_ERR(auth))
 292                 return ERR_PTR(PTR_ERR(auth));
 293
 294         enc_name = crypto_attr_alg_name(tb[2]);
 295         err = PTR_ERR(enc_name);
 296         if (IS_ERR(enc_name))
 297                 goto out_put_auth;
 298
 299         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 300         err = -ENOMEM;
 301         if (!inst)
 302                 goto out_put_auth;
 303
 304         ctx = crypto_instance_ctx(inst);
 305
 306         err = crypto_init_spawn(&ctx->auth, auth, inst, CRYPTO_ALG_TYPE_MASK);
 307         if (err)
 308                 goto err_free_inst;
 309
 310         crypto_set_skcipher_spawn(&ctx->enc, inst);
 311         err = crypto_grab_skcipher(&ctx->enc, enc_name, 0,
 312                                    crypto_requires_sync(algt->type,
 313                                                         algt->mask));
 314         if (err)
 315                 goto err_drop_auth;
 316
 317         enc = crypto_skcipher_spawn_alg(&ctx->enc);
 318
 319         err = -ENAMETOOLONG;
 320         if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
 321                      "authenc(%s,%s)", auth->cra_name, enc->cra_name) >=
 322             CRYPTO_MAX_ALG_NAME)
 323                 goto err_drop_enc;
 324
 325         if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 326                      "authenc(%s,%s)", auth->cra_driver_name,
 327                      enc->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 328                 goto err_drop_enc;
 329
 330         inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD;
 331         inst->alg.cra_flags |= enc->cra_flags & CRYPTO_ALG_ASYNC;
 332         inst->alg.cra_priority = enc->cra_priority * 10 + auth->cra_priority;
 333         inst->alg.cra_blocksize = enc->cra_blocksize;
 334         inst->alg.cra_alignmask = auth->cra_alignmask | enc->cra_alignmask;
 335         inst->alg.cra_type = &crypto_aead_type;
 336
 337         inst->alg.cra_aead.ivsize = enc->cra_ablkcipher.ivsize;
 338         inst->alg.cra_aead.maxauthsize = auth->cra_type == &crypto_hash_type ?
 339                                          auth->cra_hash.digestsize :
 340                                          auth->cra_digest.dia_digestsize;
 341
 342         inst->alg.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
 343
 344         inst->alg.cra_init = crypto_authenc_init_tfm;
 345         inst->alg.cra_exit = crypto_authenc_exit_tfm;
 346
 347         inst->alg.cra_aead.setkey = crypto_authenc_setkey;
 348         inst->alg.cra_aead.encrypt = crypto_authenc_encrypt;
 349         inst->alg.cra_aead.decrypt = crypto_authenc_decrypt;
 350
 351 out:
 352         crypto_mod_put(auth);
 353         return inst;
 354
 355 err_drop_enc:
 356         crypto_drop_skcipher(&ctx->enc);
 357 err_drop_auth:
 358         crypto_drop_spawn(&ctx->auth);
 359 err_free_inst:
 360         kfree(inst);
 361 out_put_auth:
 362         inst = ERR_PTR(err);
 363         goto out;
 364 }
 365
 366 static void crypto_authenc_free(struct crypto_instance *inst)
 367 {
 368         struct authenc_instance_ctx *ctx = crypto_instance_ctx(inst);
 369
 370         crypto_drop_skcipher(&ctx->enc);
 371         crypto_drop_spawn(&ctx->auth);
 372         kfree(inst);
 373 }
 374
 375 static struct crypto_template crypto_authenc_tmpl = {
 376         .name = "authenc",
 377         .alloc = crypto_authenc_alloc,
 378         .free = crypto_authenc_free,
 379         .module = THIS_MODULE,
 380 };
 381
 382 static int __init crypto_authenc_module_init(void)
 383 {
 384         return crypto_register_template(&crypto_authenc_tmpl);
 385 }
 386
 387 static void __exit crypto_authenc_module_exit(void)
 388 {
 389         crypto_unregister_template(&crypto_authenc_tmpl);
 390 }
 391
 392 module_init(crypto_authenc_module_init);
 393 module_exit(crypto_authenc_module_exit);
 394
 395 MODULE_LICENSE("GPL");
 396 MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");