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 <linux/err.h>
  15 #include <linux/init.h>
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/slab.h>
  19 #include <linux/spinlock.h>
  20
  21 #include "scatterwalk.h"
  22
  23 struct authenc_instance_ctx {
  24         struct crypto_spawn auth;
  25         struct crypto_spawn enc;
  26
  27         unsigned int authsize;
  28         unsigned int enckeylen;
  29 };
  30
  31 struct crypto_authenc_ctx {
  32         spinlock_t auth_lock;
  33         struct crypto_hash *auth;
  34         struct crypto_ablkcipher *enc;
  35 };
  36
  37 static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
  38                                  unsigned int keylen)
  39 {
  40         struct authenc_instance_ctx *ictx =
  41                 crypto_instance_ctx(crypto_aead_alg_instance(authenc));
  42         unsigned int enckeylen = ictx->enckeylen;
  43         unsigned int authkeylen;
  44         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  45         struct crypto_hash *auth = ctx->auth;
  46         struct crypto_ablkcipher *enc = ctx->enc;
  47         int err = -EINVAL;
  48
  49         if (keylen < enckeylen) {
  50                 crypto_aead_set_flags(authenc, CRYPTO_TFM_RES_BAD_KEY_LEN);
  51                 goto out;
  52         }
  53         authkeylen = keylen - enckeylen;
  54
  55         crypto_hash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
  56         crypto_hash_set_flags(auth, crypto_aead_get_flags(authenc) &
  57                                     CRYPTO_TFM_REQ_MASK);
  58         err = crypto_hash_setkey(auth, key, authkeylen);
  59         crypto_aead_set_flags(authenc, crypto_hash_get_flags(auth) &
  60                                        CRYPTO_TFM_RES_MASK);
  61
  62         if (err)
  63                 goto out;
  64
  65         crypto_ablkcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
  66         crypto_ablkcipher_set_flags(enc, crypto_aead_get_flags(authenc) &
  67                                          CRYPTO_TFM_REQ_MASK);
  68         err = crypto_ablkcipher_setkey(enc, key + authkeylen, enckeylen);
  69         crypto_aead_set_flags(authenc, crypto_ablkcipher_get_flags(enc) &
  70                                        CRYPTO_TFM_RES_MASK);
  71
  72 out:
  73         return err;
  74 }
  75
  76 static int crypto_authenc_hash(struct aead_request *req)
  77 {
  78         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
  79         struct authenc_instance_ctx *ictx =
  80                 crypto_instance_ctx(crypto_aead_alg_instance(authenc));
  81         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  82         struct crypto_hash *auth = ctx->auth;
  83         struct hash_desc desc = {
  84                 .tfm = auth,
  85         };
  86         u8 *hash = aead_request_ctx(req);
  87         struct scatterlist *dst = req->dst;
  88         unsigned int cryptlen = req->cryptlen;
  89         int err;
  90
  91         hash = (u8 *)ALIGN((unsigned long)hash + crypto_hash_alignmask(auth),
  92                            crypto_hash_alignmask(auth) + 1);
  93
  94         spin_lock_bh(&ctx->auth_lock);
  95         err = crypto_hash_init(&desc);
  96         if (err)
  97                 goto auth_unlock;
  98
  99         err = crypto_hash_update(&desc, req->assoc, req->assoclen);
 100         if (err)
 101                 goto auth_unlock;
 102
 103         err = crypto_hash_update(&desc, dst, cryptlen);
 104         if (err)
 105                 goto auth_unlock;
 106
 107         err = crypto_hash_final(&desc, hash);
 108 auth_unlock:
 109         spin_unlock_bh(&ctx->auth_lock);
 110
 111         if (err)
 112                 return err;
 113
 114         scatterwalk_map_and_copy(hash, dst, cryptlen, ictx->authsize, 1);
 115         return 0;
 116 }
 117
 118 static void crypto_authenc_encrypt_done(struct crypto_async_request *req,
 119                                         int err)
 120 {
 121         if (!err)
 122                 err = crypto_authenc_hash(req->data);
 123
 124         aead_request_complete(req->data, err);
 125 }
 126
 127 static int crypto_authenc_encrypt(struct aead_request *req)
 128 {
 129         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 130         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 131         struct ablkcipher_request *abreq = aead_request_ctx(req);
 132         int err;
 133
 134         ablkcipher_request_set_tfm(abreq, ctx->enc);
 135         ablkcipher_request_set_callback(abreq, aead_request_flags(req),
 136                                         crypto_authenc_encrypt_done, req);
 137         ablkcipher_request_set_crypt(abreq, req->src, req->dst, req->cryptlen,
 138                                      req->iv);
 139
 140         err = crypto_ablkcipher_encrypt(abreq);
 141         if (err)
 142                 return err;
 143
 144         return crypto_authenc_hash(req);
 145 }
 146
 147 static int crypto_authenc_verify(struct aead_request *req)
 148 {
 149         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 150         struct authenc_instance_ctx *ictx =
 151                 crypto_instance_ctx(crypto_aead_alg_instance(authenc));
 152         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 153         struct crypto_hash *auth = ctx->auth;
 154         struct hash_desc desc = {
 155                 .tfm = auth,
 156                 .flags = aead_request_flags(req),
 157         };
 158         u8 *ohash = aead_request_ctx(req);
 159         u8 *ihash;
 160         struct scatterlist *src = req->src;
 161         unsigned int cryptlen = req->cryptlen;
 162         unsigned int authsize;
 163         int err;
 164
 165         ohash = (u8 *)ALIGN((unsigned long)ohash + crypto_hash_alignmask(auth),
 166                             crypto_hash_alignmask(auth) + 1);
 167         ihash = ohash + crypto_hash_digestsize(auth);
 168
 169         spin_lock_bh(&ctx->auth_lock);
 170         err = crypto_hash_init(&desc);
 171         if (err)
 172                 goto auth_unlock;
 173
 174         err = crypto_hash_update(&desc, req->assoc, req->assoclen);
 175         if (err)
 176                 goto auth_unlock;
 177
 178         err = crypto_hash_update(&desc, src, cryptlen);
 179         if (err)
 180                 goto auth_unlock;
 181
 182         err = crypto_hash_final(&desc, ohash);
 183 auth_unlock:
 184         spin_unlock_bh(&ctx->auth_lock);
 185
 186         if (err)
 187                 return err;
 188
 189         authsize = ictx->authsize;
 190         scatterwalk_map_and_copy(ihash, src, cryptlen, authsize, 0);
 191         return memcmp(ihash, ohash, authsize) ? -EINVAL : 0;
 192 }
 193
 194 static void crypto_authenc_decrypt_done(struct crypto_async_request *req,
 195                                         int err)
 196 {
 197         aead_request_complete(req->data, err);
 198 }
 199
 200 static int crypto_authenc_decrypt(struct aead_request *req)
 201 {
 202         struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 203         struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 204         struct ablkcipher_request *abreq = aead_request_ctx(req);
 205         int err;
 206
 207         err = crypto_authenc_verify(req);
 208         if (err)
 209                 return err;
 210
 211         ablkcipher_request_set_tfm(abreq, ctx->enc);
 212         ablkcipher_request_set_callback(abreq, aead_request_flags(req),
 213                                         crypto_authenc_decrypt_done, req);
 214         ablkcipher_request_set_crypt(abreq, req->src, req->dst, req->cryptlen,
 215                                      req->iv);
 216
 217         return crypto_ablkcipher_decrypt(abreq);
 218 }
 219
 220 static int crypto_authenc_init_tfm(struct crypto_tfm *tfm)
 221 {
 222         struct crypto_instance *inst = (void *)tfm->__crt_alg;
 223         struct authenc_instance_ctx *ictx = crypto_instance_ctx(inst);
 224         struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
 225         struct crypto_hash *auth;
 226         struct crypto_ablkcipher *enc;
 227         unsigned int digestsize;
 228         int err;
 229
 230         auth = crypto_spawn_hash(&ictx->auth);
 231         if (IS_ERR(auth))
 232                 return PTR_ERR(auth);
 233
 234         err = -EINVAL;
 235         digestsize = crypto_hash_digestsize(auth);
 236         if (ictx->authsize > digestsize)
 237                 goto err_free_hash;
 238
 239         enc = crypto_spawn_ablkcipher(&ictx->enc);
 240         err = PTR_ERR(enc);
 241         if (IS_ERR(enc))
 242                 goto err_free_hash;
 243
 244         ctx->auth = auth;
 245         ctx->enc = enc;
 246         tfm->crt_aead.reqsize = max_t(unsigned int,
 247                                       (crypto_hash_alignmask(auth) &
 248                                        ~(crypto_tfm_ctx_alignment() - 1)) +
 249                                       digestsize * 2,
 250                                       sizeof(struct ablkcipher_request) +
 251                                       crypto_ablkcipher_reqsize(enc));
 252
 253         spin_lock_init(&ctx->auth_lock);
 254
 255         return 0;
 256
 257 err_free_hash:
 258         crypto_free_hash(auth);
 259         return err;
 260 }
 261
 262 static void crypto_authenc_exit_tfm(struct crypto_tfm *tfm)
 263 {
 264         struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
 265
 266         crypto_free_hash(ctx->auth);
 267         crypto_free_ablkcipher(ctx->enc);
 268 }
 269
 270 static struct crypto_instance *crypto_authenc_alloc(struct rtattr **tb)
 271 {
 272         struct crypto_instance *inst;
 273         struct crypto_alg *auth;
 274         struct crypto_alg *enc;
 275         struct authenc_instance_ctx *ctx;
 276         unsigned int authsize;
 277         unsigned int enckeylen;
 278         int err;
 279
 280         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD);
 281         if (err)
 282                 return ERR_PTR(err);
 283
 284         auth = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
 285                                CRYPTO_ALG_TYPE_HASH_MASK);
 286         if (IS_ERR(auth))
 287                 return ERR_PTR(PTR_ERR(auth));
 288
 289         err = crypto_attr_u32(tb[2], &authsize);
 290         inst = ERR_PTR(err);
 291         if (err)
 292                 goto out_put_auth;
 293
 294         enc = crypto_attr_alg(tb[3], CRYPTO_ALG_TYPE_BLKCIPHER,
 295                               CRYPTO_ALG_TYPE_MASK);
 296         inst = ERR_PTR(PTR_ERR(enc));
 297         if (IS_ERR(enc))
 298                 goto out_put_auth;
 299
 300         err = crypto_attr_u32(tb[4], &enckeylen);
 301         if (err)
 302                 goto out_put_enc;
 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,%u,%s,%u)", auth->cra_name, authsize,
 312                      enc->cra_name, enckeylen) >= 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,%u,%s,%u)", auth->cra_driver_name,
 317                      authsize, enc->cra_driver_name, enckeylen) >=
 318             CRYPTO_MAX_ALG_NAME)
 319                 goto err_free_inst;
 320
 321         ctx = crypto_instance_ctx(inst);
 322         ctx->authsize = authsize;
 323         ctx->enckeylen = enckeylen;
 324
 325         err = crypto_init_spawn(&ctx->auth, auth, inst, CRYPTO_ALG_TYPE_MASK);
 326         if (err)
 327                 goto err_free_inst;
 328
 329         err = crypto_init_spawn(&ctx->enc, enc, inst, CRYPTO_ALG_TYPE_MASK);
 330         if (err)
 331                 goto err_drop_auth;
 332
 333         inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD | CRYPTO_ALG_ASYNC;
 334         inst->alg.cra_priority = enc->cra_priority * 10 + auth->cra_priority;
 335         inst->alg.cra_blocksize = enc->cra_blocksize;
 336         inst->alg.cra_alignmask = max(auth->cra_alignmask, enc->cra_alignmask);
 337         inst->alg.cra_type = &crypto_aead_type;
 338
 339         inst->alg.cra_aead.ivsize = enc->cra_blkcipher.ivsize;
 340         inst->alg.cra_aead.authsize = authsize;
 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(enc);
 353 out_put_auth:
 354         crypto_mod_put(auth);
 355         return inst;
 356
 357 err_drop_auth:
 358         crypto_drop_spawn(&ctx->auth);
 359 err_free_inst:
 360         kfree(inst);
 361 out_put_enc:
 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_spawn(&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");