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/algapi.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_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 (keylen < sizeof(*rta))
  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 int crypto_authenc_hash(struct aead_request *req)
  91 {
  92         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
  93         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  94         struct crypto_hash *auth = ctx->auth;
  95         struct hash_desc desc = {
  96                 .tfm = auth,
  97         };
  98         u8 *hash = aead_request_ctx(req);
  99         struct scatterlist *dst = req->dst;
 100         unsigned int cryptlen = req->cryptlen;
 101         int err;
 102
 103         hash = (u8 *)ALIGN((unsigned long)hash + crypto_hash_alignmask(auth),
 104                            crypto_hash_alignmask(auth) + 1);
 105
 106         spin_lock_bh(&ctx->auth_lock);
 107         err = crypto_hash_init(&desc);
 108         if (err)
 109                 goto auth_unlock;
 110
 111         err = crypto_hash_update(&desc, req->assoc, req->assoclen);
 112         if (err)
 113                 goto auth_unlock;
 114
 115         err = crypto_hash_update(&desc, dst, cryptlen);
 116         if (err)
 117                 goto auth_unlock;
 118
 119         err = crypto_hash_final(&desc, hash);
 120 auth_unlock:
 121         spin_unlock_bh(&ctx->auth_lock);
 122
 123         if (err)
 124                 return err;
 125
 126         scatterwalk_map_and_copy(hash, dst, cryptlen,
 127                                  crypto_aead_authsize(authenc), 1);
 128         return 0;
 129 }
 130
 131 static void crypto_authenc_encrypt_done(struct crypto_async_request *req,
 132                                         int err)
 133 {
 134         if (!err)
 135                 err = crypto_authenc_hash(req->data);
 136
 137         aead_request_complete(req->data, err);
 138 }
 139
 140 static int crypto_authenc_encrypt(struct aead_request *req)
 141 {
 142         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 143         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 144         struct ablkcipher_request *abreq = aead_request_ctx(req);
 145         int err;
 146
 147         ablkcipher_request_set_tfm(abreq, ctx->enc);
 148         ablkcipher_request_set_callback(abreq, aead_request_flags(req),
 149                                         crypto_authenc_encrypt_done, req);
 150         ablkcipher_request_set_crypt(abreq, req->src, req->dst, req->cryptlen,
 151                                      req->iv);
 152
 153         err = crypto_ablkcipher_encrypt(abreq);
 154         if (err)
 155                 return err;
 156
 157         return crypto_authenc_hash(req);
 158 }
 159
 160 static int crypto_authenc_verify(struct aead_request *req,
 161                                  unsigned int cryptlen)
 162 {
 163         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 164         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 165         struct crypto_hash *auth = ctx->auth;
 166         struct hash_desc desc = {
 167                 .tfm = auth,
 168                 .flags = aead_request_flags(req),
 169         };
 170         u8 *ohash = aead_request_ctx(req);
 171         u8 *ihash;
 172         struct scatterlist *src = req->src;
 173         unsigned int authsize;
 174         int err;
 175
 176         ohash = (u8 *)ALIGN((unsigned long)ohash + crypto_hash_alignmask(auth),
 177                             crypto_hash_alignmask(auth) + 1);
 178         ihash = ohash + crypto_hash_digestsize(auth);
 179
 180         spin_lock_bh(&ctx->auth_lock);
 181         err = crypto_hash_init(&desc);
 182         if (err)
 183                 goto auth_unlock;
 184
 185         err = crypto_hash_update(&desc, req->assoc, req->assoclen);
 186         if (err)
 187                 goto auth_unlock;
 188
 189         err = crypto_hash_update(&desc, src, cryptlen);
 190         if (err)
 191                 goto auth_unlock;
 192
 193         err = crypto_hash_final(&desc, ohash);
 194 auth_unlock:
 195         spin_unlock_bh(&ctx->auth_lock);
 196
 197         if (err)
 198                 return err;
 199
 200         authsize = crypto_aead_authsize(authenc);
 201         scatterwalk_map_and_copy(ihash, src, cryptlen, authsize, 0);
 202         return memcmp(ihash, ohash, authsize) ? -EBADMSG: 0;
 203 }
 204
 205 static void crypto_authenc_decrypt_done(struct crypto_async_request *req,
 206                                         int err)
 207 {
 208         aead_request_complete(req->data, err);
 209 }
 210
 211 static int crypto_authenc_decrypt(struct aead_request *req)
 212 {
 213         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 214         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 215         struct ablkcipher_request *abreq = aead_request_ctx(req);
 216         unsigned int cryptlen = req->cryptlen;
 217         unsigned int authsize = crypto_aead_authsize(authenc);
 218         int err;
 219
 220         if (cryptlen < authsize)
 221                 return -EINVAL;
 222         cryptlen -= authsize;
 223
 224         err = crypto_authenc_verify(req, cryptlen);
 225         if (err)
 226                 return err;
 227
 228         ablkcipher_request_set_tfm(abreq, ctx->enc);
 229         ablkcipher_request_set_callback(abreq, aead_request_flags(req),
 230                                         crypto_authenc_decrypt_done, req);
 231         ablkcipher_request_set_crypt(abreq, req->src, req->dst, cryptlen,
 232                                      req->iv);
 233
 234         return crypto_ablkcipher_decrypt(abreq);
 235 }
 236
 237 static int crypto_authenc_init_tfm(struct crypto_tfm *tfm)
 238 {
 239         struct crypto_instance *inst = (void *)tfm->__crt_alg;
 240         struct authenc_instance_ctx *ictx = crypto_instance_ctx(inst);
 241         struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
 242         struct crypto_hash *auth;
 243         struct crypto_ablkcipher *enc;
 244         int err;
 245
 246         auth = crypto_spawn_hash(&ictx->auth);
 247         if (IS_ERR(auth))
 248                 return PTR_ERR(auth);
 249
 250         enc = crypto_spawn_ablkcipher(&ictx->enc);
 251         err = PTR_ERR(enc);
 252         if (IS_ERR(enc))
 253                 goto err_free_hash;
 254
 255         ctx->auth = auth;
 256         ctx->enc = enc;
 257         tfm->crt_aead.reqsize = max_t(unsigned int,
 258                                       (crypto_hash_alignmask(auth) &
 259                                        ~(crypto_tfm_ctx_alignment() - 1)) +
 260                                       crypto_hash_digestsize(auth) * 2,
 261                                       sizeof(struct ablkcipher_request) +
 262                                       crypto_ablkcipher_reqsize(enc));
 263
 264         spin_lock_init(&ctx->auth_lock);
 265
 266         return 0;
 267
 268 err_free_hash:
 269         crypto_free_hash(auth);
 270         return err;
 271 }
 272
 273 static void crypto_authenc_exit_tfm(struct crypto_tfm *tfm)
 274 {
 275         struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
 276
 277         crypto_free_hash(ctx->auth);
 278         crypto_free_ablkcipher(ctx->enc);
 279 }
 280
 281 static struct crypto_instance *crypto_authenc_alloc(struct rtattr **tb)
 282 {
 283         struct crypto_instance *inst;
 284         struct crypto_alg *auth;
 285         struct crypto_alg *enc;
 286         struct authenc_instance_ctx *ctx;
 287         int err;
 288
 289         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD);
 290         if (err)
 291                 return ERR_PTR(err);
 292
 293         auth = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
 294                                CRYPTO_ALG_TYPE_HASH_MASK);
 295         if (IS_ERR(auth))
 296                 return ERR_PTR(PTR_ERR(auth));
 297
 298         enc = crypto_attr_alg(tb[2], CRYPTO_ALG_TYPE_BLKCIPHER,
 299                               CRYPTO_ALG_TYPE_BLKCIPHER_MASK);
 300         inst = ERR_PTR(PTR_ERR(enc));
 301         if (IS_ERR(enc))
 302                 goto out_put_auth;
 303
 304         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 305         err = -ENOMEM;
 306         if (!inst)
 307                 goto out_put_enc;
 308
 309         err = -ENAMETOOLONG;
 310         if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
 311                      "authenc(%s,%s)", auth->cra_name, enc->cra_name) >=
 312             CRYPTO_MAX_ALG_NAME)
 313                 goto err_free_inst;
 314
 315         if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 316                      "authenc(%s,%s)", auth->cra_driver_name,
 317                      enc->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 318                 goto err_free_inst;
 319
 320         ctx = crypto_instance_ctx(inst);
 321
 322         err = crypto_init_spawn(&ctx->auth, auth, inst, CRYPTO_ALG_TYPE_MASK);
 323         if (err)
 324                 goto err_free_inst;
 325
 326         err = crypto_init_spawn(&ctx->enc, enc, inst, CRYPTO_ALG_TYPE_MASK);
 327         if (err)
 328                 goto err_drop_auth;
 329
 330         inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD | CRYPTO_ALG_ASYNC;
 331         inst->alg.cra_priority = enc->cra_priority * 10 + auth->cra_priority;
 332         inst->alg.cra_blocksize = enc->cra_blocksize;
 333         inst->alg.cra_alignmask = auth->cra_alignmask | enc->cra_alignmask;
 334         inst->alg.cra_type = &crypto_aead_type;
 335
 336         inst->alg.cra_aead.ivsize = enc->cra_blkcipher.ivsize;
 337         inst->alg.cra_aead.maxauthsize = auth->cra_type == &crypto_hash_type ?
 338                                          auth->cra_hash.digestsize :
 339                                          auth->cra_digest.dia_digestsize;
 340
 341         inst->alg.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
 342
 343         inst->alg.cra_init = crypto_authenc_init_tfm;
 344         inst->alg.cra_exit = crypto_authenc_exit_tfm;
 345
 346         inst->alg.cra_aead.setkey = crypto_authenc_setkey;
 347         inst->alg.cra_aead.encrypt = crypto_authenc_encrypt;
 348         inst->alg.cra_aead.decrypt = crypto_authenc_decrypt;
 349
 350 out:
 351         crypto_mod_put(enc);
 352 out_put_auth:
 353         crypto_mod_put(auth);
 354         return inst;
 355
 356 err_drop_auth:
 357         crypto_drop_spawn(&ctx->auth);
 358 err_free_inst:
 359         kfree(inst);
 360 out_put_enc:
 361         inst = ERR_PTR(err);
 362         goto out;
 363 }
 364
 365 static void crypto_authenc_free(struct crypto_instance *inst)
 366 {
 367         struct authenc_instance_ctx *ctx = crypto_instance_ctx(inst);
 368
 369         crypto_drop_spawn(&ctx->enc);
 370         crypto_drop_spawn(&ctx->auth);
 371         kfree(inst);
 372 }
 373
 374 static struct crypto_template crypto_authenc_tmpl = {
 375         .name = "authenc",
 376         .alloc = crypto_authenc_alloc,
 377         .free = crypto_authenc_free,
 378         .module = THIS_MODULE,
 379 };
 380
 381 static int __init crypto_authenc_module_init(void)
 382 {
 383         return crypto_register_template(&crypto_authenc_tmpl);
 384 }
 385
 386 static void __exit crypto_authenc_module_exit(void)
 387 {
 388         crypto_unregister_template(&crypto_authenc_tmpl);
 389 }
 390
 391 module_init(crypto_authenc_module_init);
 392 module_exit(crypto_authenc_module_exit);
 393
 394 MODULE_LICENSE("GPL");
 395 MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");