crypto/chainiv.c

   1 /*
   2  * chainiv: Chain IV Generator
   3  *
   4  * Generate IVs simply be using the last block of the previous encryption.
   5  * This is mainly useful for CBC with a synchronous algorithm.
   6  *
   7  * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU General Public License as published by the Free
  11  * Software Foundation; either version 2 of the License, or (at your option)
  12  * any later version.
  13  *
  14  */
  15
  16 #include <crypto/internal/skcipher.h>
  17 #include <crypto/rng.h>
  18 #include <crypto/crypto_wq.h>
  19 #include <linux/err.h>
  20 #include <linux/init.h>
  21 #include <linux/kernel.h>
  22 #include <linux/module.h>
  23 #include <linux/spinlock.h>
  24 #include <linux/string.h>
  25 #include <linux/workqueue.h>
  26
  27 enum {
  28         CHAINIV_STATE_INUSE = 0,
  29 };
  30
  31 struct chainiv_ctx {
  32         spinlock_t lock;
  33         char iv[];
  34 };
  35
  36 struct async_chainiv_ctx {
  37         unsigned long state;
  38
  39         spinlock_t lock;
  40         int err;
  41
  42         struct crypto_queue queue;
  43         struct work_struct postponed;
  44
  45         char iv[];
  46 };
  47
  48 static int chainiv_givencrypt(struct skcipher_givcrypt_request *req)
  49 {
  50         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
  51         struct chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
  52         struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
  53         unsigned int ivsize;
  54         int err;
  55
  56         ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
  57         ablkcipher_request_set_callback(subreq, req->creq.base.flags &
  58                                                 ~CRYPTO_TFM_REQ_MAY_SLEEP,
  59                                         req->creq.base.complete,
  60                                         req->creq.base.data);
  61         ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
  62                                      req->creq.nbytes, req->creq.info);
  63
  64         spin_lock_bh(&ctx->lock);
  65
  66         ivsize = crypto_ablkcipher_ivsize(geniv);
  67
  68         memcpy(req->giv, ctx->iv, ivsize);
  69         memcpy(subreq->info, ctx->iv, ivsize);
  70
  71         err = crypto_ablkcipher_encrypt(subreq);
  72         if (err)
  73                 goto unlock;
  74
  75         memcpy(ctx->iv, subreq->info, ivsize);
  76
  77 unlock:
  78         spin_unlock_bh(&ctx->lock);
  79
  80         return err;
  81 }
  82
  83 static int chainiv_givencrypt_first(struct skcipher_givcrypt_request *req)
  84 {
  85         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
  86         struct chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
  87         int err = 0;
  88
  89         spin_lock_bh(&ctx->lock);
  90         if (crypto_ablkcipher_crt(geniv)->givencrypt !=
  91             chainiv_givencrypt_first)
  92                 goto unlock;
  93
  94         crypto_ablkcipher_crt(geniv)->givencrypt = chainiv_givencrypt;
  95         err = crypto_rng_get_bytes(crypto_default_rng, ctx->iv,
  96                                    crypto_ablkcipher_ivsize(geniv));
  97
  98 unlock:
  99         spin_unlock_bh(&ctx->lock);
 100
 101         if (err)
 102                 return err;
 103
 104         return chainiv_givencrypt(req);
 105 }
 106
 107 static int chainiv_init_common(struct crypto_tfm *tfm)
 108 {
 109         tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request);
 110
 111         return skcipher_geniv_init(tfm);
 112 }
 113
 114 static int chainiv_init(struct crypto_tfm *tfm)
 115 {
 116         struct chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
 117
 118         spin_lock_init(&ctx->lock);
 119
 120         return chainiv_init_common(tfm);
 121 }
 122
 123 static int async_chainiv_schedule_work(struct async_chainiv_ctx *ctx)
 124 {
 125         int queued;
 126         int err = ctx->err;
 127
 128         if (!ctx->queue.qlen) {
 129                 smp_mb__before_clear_bit();
 130                 clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
 131
 132                 if (!ctx->queue.qlen ||
 133                     test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
 134                         goto out;
 135         }
 136
 137         queued = queue_work(kcrypto_wq, &ctx->postponed);
 138         BUG_ON(!queued);
 139
 140 out:
 141         return err;
 142 }
 143
 144 static int async_chainiv_postpone_request(struct skcipher_givcrypt_request *req)
 145 {
 146         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
 147         struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
 148         int err;
 149
 150         spin_lock_bh(&ctx->lock);
 151         err = skcipher_enqueue_givcrypt(&ctx->queue, req);
 152         spin_unlock_bh(&ctx->lock);
 153
 154         if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
 155                 return err;
 156
 157         ctx->err = err;
 158         return async_chainiv_schedule_work(ctx);
 159 }
 160
 161 static int async_chainiv_givencrypt_tail(struct skcipher_givcrypt_request *req)
 162 {
 163         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
 164         struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
 165         struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
 166         unsigned int ivsize = crypto_ablkcipher_ivsize(geniv);
 167
 168         memcpy(req->giv, ctx->iv, ivsize);
 169         memcpy(subreq->info, ctx->iv, ivsize);
 170
 171         ctx->err = crypto_ablkcipher_encrypt(subreq);
 172         if (ctx->err)
 173                 goto out;
 174
 175         memcpy(ctx->iv, subreq->info, ivsize);
 176
 177 out:
 178         return async_chainiv_schedule_work(ctx);
 179 }
 180
 181 static int async_chainiv_givencrypt(struct skcipher_givcrypt_request *req)
 182 {
 183         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
 184         struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
 185         struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
 186
 187         ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
 188         ablkcipher_request_set_callback(subreq, req->creq.base.flags,
 189                                         req->creq.base.complete,
 190                                         req->creq.base.data);
 191         ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
 192                                      req->creq.nbytes, req->creq.info);
 193
 194         if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
 195                 goto postpone;
 196
 197         if (ctx->queue.qlen) {
 198                 clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
 199                 goto postpone;
 200         }
 201
 202         return async_chainiv_givencrypt_tail(req);
 203
 204 postpone:
 205         return async_chainiv_postpone_request(req);
 206 }
 207
 208 static int async_chainiv_givencrypt_first(struct skcipher_givcrypt_request *req)
 209 {
 210         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
 211         struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
 212         int err = 0;
 213
 214         if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
 215                 goto out;
 216
 217         if (crypto_ablkcipher_crt(geniv)->givencrypt !=
 218             async_chainiv_givencrypt_first)
 219                 goto unlock;
 220
 221         crypto_ablkcipher_crt(geniv)->givencrypt = async_chainiv_givencrypt;
 222         err = crypto_rng_get_bytes(crypto_default_rng, ctx->iv,
 223                                    crypto_ablkcipher_ivsize(geniv));
 224
 225 unlock:
 226         clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
 227
 228         if (err)
 229                 return err;
 230
 231 out:
 232         return async_chainiv_givencrypt(req);
 233 }
 234
 235 static void async_chainiv_do_postponed(struct work_struct *work)
 236 {
 237         struct async_chainiv_ctx *ctx = container_of(work,
 238                                                      struct async_chainiv_ctx,
 239                                                      postponed);
 240         struct skcipher_givcrypt_request *req;
 241         struct ablkcipher_request *subreq;
 242         int err;
 243
 244         /* Only handle one request at a time to avoid hogging keventd. */
 245         spin_lock_bh(&ctx->lock);
 246         req = skcipher_dequeue_givcrypt(&ctx->queue);
 247         spin_unlock_bh(&ctx->lock);
 248
 249         if (!req) {
 250                 async_chainiv_schedule_work(ctx);
 251                 return;
 252         }
 253
 254         subreq = skcipher_givcrypt_reqctx(req);
 255         subreq->base.flags |= CRYPTO_TFM_REQ_MAY_SLEEP;
 256
 257         err = async_chainiv_givencrypt_tail(req);
 258
 259         local_bh_disable();
 260         skcipher_givcrypt_complete(req, err);
 261         local_bh_enable();
 262 }
 263
 264 static int async_chainiv_init(struct crypto_tfm *tfm)
 265 {
 266         struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
 267
 268         spin_lock_init(&ctx->lock);
 269
 270         crypto_init_queue(&ctx->queue, 100);
 271         INIT_WORK(&ctx->postponed, async_chainiv_do_postponed);
 272
 273         return chainiv_init_common(tfm);
 274 }
 275
 276 static void async_chainiv_exit(struct crypto_tfm *tfm)
 277 {
 278         struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
 279
 280         BUG_ON(test_bit(CHAINIV_STATE_INUSE, &ctx->state) || ctx->queue.qlen);
 281
 282         skcipher_geniv_exit(tfm);
 283 }
 284
 285 static struct crypto_template chainiv_tmpl;
 286
 287 static struct crypto_instance *chainiv_alloc(struct rtattr **tb)
 288 {
 289         struct crypto_attr_type *algt;
 290         struct crypto_instance *inst;
 291         int err;
 292
 293         algt = crypto_get_attr_type(tb);
 294         if (IS_ERR(algt))
 295                 return ERR_CAST(algt);
 296
 297         err = crypto_get_default_rng();
 298         if (err)
 299                 return ERR_PTR(err);
 300
 301         inst = skcipher_geniv_alloc(&chainiv_tmpl, tb, 0, 0);
 302         if (IS_ERR(inst))
 303                 goto put_rng;
 304
 305         inst->alg.cra_ablkcipher.givencrypt = chainiv_givencrypt_first;
 306
 307         inst->alg.cra_init = chainiv_init;
 308         inst->alg.cra_exit = skcipher_geniv_exit;
 309
 310         inst->alg.cra_ctxsize = sizeof(struct chainiv_ctx);
 311
 312         if (!crypto_requires_sync(algt->type, algt->mask)) {
 313                 inst->alg.cra_flags |= CRYPTO_ALG_ASYNC;
 314
 315                 inst->alg.cra_ablkcipher.givencrypt =
 316                         async_chainiv_givencrypt_first;
 317
 318                 inst->alg.cra_init = async_chainiv_init;
 319                 inst->alg.cra_exit = async_chainiv_exit;
 320
 321                 inst->alg.cra_ctxsize = sizeof(struct async_chainiv_ctx);
 322         }
 323
 324         inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize;
 325
 326 out:
 327         return inst;
 328
 329 put_rng:
 330         crypto_put_default_rng();
 331         goto out;
 332 }
 333
 334 static void chainiv_free(struct crypto_instance *inst)
 335 {
 336         skcipher_geniv_free(inst);
 337         crypto_put_default_rng();
 338 }
 339
 340 static struct crypto_template chainiv_tmpl = {
 341         .name = "chainiv",
 342         .alloc = chainiv_alloc,
 343         .free = chainiv_free,
 344         .module = THIS_MODULE,
 345 };
 346
 347 static int __init chainiv_module_init(void)
 348 {
 349         return crypto_register_template(&chainiv_tmpl);
 350 }
 351
 352 static void chainiv_module_exit(void)
 353 {
 354         crypto_unregister_template(&chainiv_tmpl);
 355 }
 356
 357 module_init(chainiv_module_init);
 358 module_exit(chainiv_module_exit);
 359
 360 MODULE_LICENSE("GPL");
 361 MODULE_DESCRIPTION("Chain IV Generator");