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 <linux/err.h>
  18 #include <linux/init.h>
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/random.h>
  22 #include <linux/spinlock.h>
  23 #include <linux/string.h>
  24 #include <linux/workqueue.h>
  25
  26 enum {
  27         CHAINIV_STATE_INUSE = 0,
  28 };
  29
  30 struct chainiv_ctx {
  31         spinlock_t lock;
  32         char iv[];
  33 };
  34
  35 struct async_chainiv_ctx {
  36         unsigned long state;
  37
  38         spinlock_t lock;
  39         int err;
  40
  41         struct crypto_queue queue;
  42         struct work_struct postponed;
  43
  44         char iv[];
  45 };
  46
  47 static int chainiv_givencrypt(struct skcipher_givcrypt_request *req)
  48 {
  49         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
  50         struct chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
  51         struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
  52         unsigned int ivsize;
  53         int err;
  54
  55         ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
  56         ablkcipher_request_set_callback(subreq, req->creq.base.flags &
  57                                                 ~CRYPTO_TFM_REQ_MAY_SLEEP,
  58                                         req->creq.base.complete,
  59                                         req->creq.base.data);
  60         ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
  61                                      req->creq.nbytes, req->creq.info);
  62
  63         spin_lock_bh(&ctx->lock);
  64
  65         ivsize = crypto_ablkcipher_ivsize(geniv);
  66
  67         memcpy(req->giv, ctx->iv, ivsize);
  68         memcpy(subreq->info, ctx->iv, ivsize);
  69
  70         err = crypto_ablkcipher_encrypt(subreq);
  71         if (err)
  72                 goto unlock;
  73
  74         memcpy(ctx->iv, subreq->info, ivsize);
  75
  76 unlock:
  77         spin_unlock_bh(&ctx->lock);
  78
  79         return err;
  80 }
  81
  82 static int chainiv_givencrypt_first(struct skcipher_givcrypt_request *req)
  83 {
  84         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
  85         struct chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
  86
  87         spin_lock_bh(&ctx->lock);
  88         if (crypto_ablkcipher_crt(geniv)->givencrypt !=
  89             chainiv_givencrypt_first)
  90                 goto unlock;
  91
  92         crypto_ablkcipher_crt(geniv)->givencrypt = chainiv_givencrypt;
  93         get_random_bytes(ctx->iv, crypto_ablkcipher_ivsize(geniv));
  94
  95 unlock:
  96         spin_unlock_bh(&ctx->lock);
  97
  98         return chainiv_givencrypt(req);
  99 }
 100
 101 static int chainiv_init_common(struct crypto_tfm *tfm)
 102 {
 103         tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request);
 104
 105         return skcipher_geniv_init(tfm);
 106 }
 107
 108 static int chainiv_init(struct crypto_tfm *tfm)
 109 {
 110         struct chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
 111
 112         spin_lock_init(&ctx->lock);
 113
 114         return chainiv_init_common(tfm);
 115 }
 116
 117 static int async_chainiv_schedule_work(struct async_chainiv_ctx *ctx)
 118 {
 119         int queued;
 120         int err = ctx->err;
 121
 122         if (!ctx->queue.qlen) {
 123                 smp_mb__before_clear_bit();
 124                 clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
 125
 126                 if (!ctx->queue.qlen ||
 127                     test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
 128                         goto out;
 129         }
 130
 131         queued = schedule_work(&ctx->postponed);
 132         BUG_ON(!queued);
 133
 134 out:
 135         return err;
 136 }
 137
 138 static int async_chainiv_postpone_request(struct skcipher_givcrypt_request *req)
 139 {
 140         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
 141         struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
 142         int err;
 143
 144         spin_lock_bh(&ctx->lock);
 145         err = skcipher_enqueue_givcrypt(&ctx->queue, req);
 146         spin_unlock_bh(&ctx->lock);
 147
 148         if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
 149                 return err;
 150
 151         ctx->err = err;
 152         return async_chainiv_schedule_work(ctx);
 153 }
 154
 155 static int async_chainiv_givencrypt_tail(struct skcipher_givcrypt_request *req)
 156 {
 157         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
 158         struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
 159         struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
 160         unsigned int ivsize = crypto_ablkcipher_ivsize(geniv);
 161
 162         memcpy(req->giv, ctx->iv, ivsize);
 163         memcpy(subreq->info, ctx->iv, ivsize);
 164
 165         ctx->err = crypto_ablkcipher_encrypt(subreq);
 166         if (ctx->err)
 167                 goto out;
 168
 169         memcpy(ctx->iv, subreq->info, ivsize);
 170
 171 out:
 172         return async_chainiv_schedule_work(ctx);
 173 }
 174
 175 static int async_chainiv_givencrypt(struct skcipher_givcrypt_request *req)
 176 {
 177         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
 178         struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
 179         struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
 180
 181         ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
 182         ablkcipher_request_set_callback(subreq, req->creq.base.flags,
 183                                         req->creq.base.complete,
 184                                         req->creq.base.data);
 185         ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
 186                                      req->creq.nbytes, req->creq.info);
 187
 188         if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
 189                 goto postpone;
 190
 191         if (ctx->queue.qlen) {
 192                 clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
 193                 goto postpone;
 194         }
 195
 196         return async_chainiv_givencrypt_tail(req);
 197
 198 postpone:
 199         return async_chainiv_postpone_request(req);
 200 }
 201
 202 static int async_chainiv_givencrypt_first(struct skcipher_givcrypt_request *req)
 203 {
 204         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
 205         struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
 206
 207         if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
 208                 goto out;
 209
 210         if (crypto_ablkcipher_crt(geniv)->givencrypt !=
 211             async_chainiv_givencrypt_first)
 212                 goto unlock;
 213
 214         crypto_ablkcipher_crt(geniv)->givencrypt = async_chainiv_givencrypt;
 215         get_random_bytes(ctx->iv, crypto_ablkcipher_ivsize(geniv));
 216
 217 unlock:
 218         clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
 219
 220 out:
 221         return async_chainiv_givencrypt(req);
 222 }
 223
 224 static void async_chainiv_do_postponed(struct work_struct *work)
 225 {
 226         struct async_chainiv_ctx *ctx = container_of(work,
 227                                                      struct async_chainiv_ctx,
 228                                                      postponed);
 229         struct skcipher_givcrypt_request *req;
 230         struct ablkcipher_request *subreq;
 231         int err;
 232
 233         /* Only handle one request at a time to avoid hogging keventd. */
 234         spin_lock_bh(&ctx->lock);
 235         req = skcipher_dequeue_givcrypt(&ctx->queue);
 236         spin_unlock_bh(&ctx->lock);
 237
 238         if (!req) {
 239                 async_chainiv_schedule_work(ctx);
 240                 return;
 241         }
 242
 243         subreq = skcipher_givcrypt_reqctx(req);
 244         subreq->base.flags |= CRYPTO_TFM_REQ_MAY_SLEEP;
 245
 246         err = async_chainiv_givencrypt_tail(req);
 247
 248         local_bh_disable();
 249         skcipher_givcrypt_complete(req, err);
 250         local_bh_enable();
 251 }
 252
 253 static int async_chainiv_init(struct crypto_tfm *tfm)
 254 {
 255         struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
 256
 257         spin_lock_init(&ctx->lock);
 258
 259         crypto_init_queue(&ctx->queue, 100);
 260         INIT_WORK(&ctx->postponed, async_chainiv_do_postponed);
 261
 262         return chainiv_init_common(tfm);
 263 }
 264
 265 static void async_chainiv_exit(struct crypto_tfm *tfm)
 266 {
 267         struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
 268
 269         BUG_ON(test_bit(CHAINIV_STATE_INUSE, &ctx->state) || ctx->queue.qlen);
 270
 271         skcipher_geniv_exit(tfm);
 272 }
 273
 274 static struct crypto_template chainiv_tmpl;
 275
 276 static struct crypto_instance *chainiv_alloc(struct rtattr **tb)
 277 {
 278         struct crypto_attr_type *algt;
 279         struct crypto_instance *inst;
 280         int err;
 281
 282         algt = crypto_get_attr_type(tb);
 283         err = PTR_ERR(algt);
 284         if (IS_ERR(algt))
 285                 return ERR_PTR(err);
 286
 287         inst = skcipher_geniv_alloc(&chainiv_tmpl, tb, 0, 0);
 288         if (IS_ERR(inst))
 289                 goto out;
 290
 291         inst->alg.cra_ablkcipher.givencrypt = chainiv_givencrypt_first;
 292
 293         inst->alg.cra_init = chainiv_init;
 294         inst->alg.cra_exit = skcipher_geniv_exit;
 295
 296         inst->alg.cra_ctxsize = sizeof(struct chainiv_ctx);
 297
 298         if (!crypto_requires_sync(algt->type, algt->mask)) {
 299                 inst->alg.cra_flags |= CRYPTO_ALG_ASYNC;
 300
 301                 inst->alg.cra_ablkcipher.givencrypt =
 302                         async_chainiv_givencrypt_first;
 303
 304                 inst->alg.cra_init = async_chainiv_init;
 305                 inst->alg.cra_exit = async_chainiv_exit;
 306
 307                 inst->alg.cra_ctxsize = sizeof(struct async_chainiv_ctx);
 308         }
 309
 310         inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize;
 311
 312 out:
 313         return inst;
 314 }
 315
 316 static struct crypto_template chainiv_tmpl = {
 317         .name = "chainiv",
 318         .alloc = chainiv_alloc,
 319         .free = skcipher_geniv_free,
 320         .module = THIS_MODULE,
 321 };
 322
 323 int __init chainiv_module_init(void)
 324 {
 325         return crypto_register_template(&chainiv_tmpl);
 326 }
 327
 328 void chainiv_module_exit(void)
 329 {
 330         crypto_unregister_template(&chainiv_tmpl);
 331 }